diff --git a/datasette/app.py b/datasette/app.py
index 6ab32f9e2e..16545cff98 100644
--- a/datasette/app.py
+++ b/datasette/app.py
@@ -2654,9 +2654,21 @@ def _fix(self, path, avoid_path_rewrites=False):
             path = f"http://localhost{path}"
         return path
 
+    def _apply_actor(self, kwargs):
+        """If ``actor=`` was supplied, convert it into a signed ds_actor cookie."""
+        actor = kwargs.pop("actor", None)
+        if actor is None:
+            return
+        cookies = dict(kwargs.get("cookies") or {})
+        if "ds_actor" in cookies:
+            raise TypeError("Cannot pass both actor= and a ds_actor cookie")
+        cookies["ds_actor"] = self.actor_cookie(actor)
+        kwargs["cookies"] = cookies
+
     async def _request(self, method, path, skip_permission_checks=False, **kwargs):
         from datasette.permissions import SkipPermissions
 
+        self._apply_actor(kwargs)
         with _DatasetteClientContext():
             if skip_permission_checks:
                 with SkipPermissions():
@@ -2722,6 +2734,7 @@ async def request(self, method, path, skip_permission_checks=False, **kwargs):
         from datasette.permissions import SkipPermissions
 
         avoid_path_rewrites = kwargs.pop("avoid_path_rewrites", None)
+        self._apply_actor(kwargs)
         with _DatasetteClientContext():
             if skip_permission_checks:
                 with SkipPermissions():
diff --git a/docs/internals.rst b/docs/internals.rst
index 1693a241a8..ba9d313163 100644
--- a/docs/internals.rst
+++ b/docs/internals.rst
@@ -1312,6 +1312,28 @@ These methods can be used with :ref:`internals_datasette_urls` - for example:
 
 For documentation on available ``**kwargs`` options and the shape of the HTTPX Response object refer to the `HTTPX Async documentation <https://www.python-httpx.org/async/>`__.
 
+.. _internals_datasette_client_actor:
+
+Authenticating as an actor
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+All ``datasette.client`` methods accept an optional ``actor=`` parameter. When set to a dictionary describing an actor, the request is made with a signed ``ds_actor`` cookie identifying that actor — as if the request had been made by a user who is signed in as that actor.
+
+This is a convenient shorthand equivalent to signing the cookie manually using ``datasette.client.actor_cookie()``.
+
+Example usage:
+
+.. code-block:: python
+
+    response = await datasette.client.get(
+        "/-/actor.json", actor={"id": "root"}
+    )
+    assert response.json() == {"actor": {"id": "root"}}
+
+This parameter works with all HTTP methods (``get``, ``post``, ``put``, ``patch``, ``delete``, ``options``, ``head``) and the generic ``request`` method.
+
+Passing both ``actor=`` and a ``ds_actor`` cookie via ``cookies=`` raises a ``TypeError``. Other unrelated cookies can be combined with ``actor=``.
+
 Bypassing permission checks
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/tests/test_api.py b/tests/test_api.py
index 95958a7291..3676c1fb8d 100644
--- a/tests/test_api.py
+++ b/tests/test_api.py
@@ -553,8 +553,7 @@ async def test_actions_json(ds_client):
     original_root_enabled = ds_client.ds.root_enabled
     try:
         ds_client.ds.root_enabled = True
-        cookies = {"ds_actor": ds_client.actor_cookie({"id": "root"})}
-        response = await ds_client.get("/-/actions.json", cookies=cookies)
+        response = await ds_client.get("/-/actions.json", actor={"id": "root"})
         data = response.json()
     finally:
         ds_client.ds.root_enabled = original_root_enabled
diff --git a/tests/test_column_types.py b/tests/test_column_types.py
index 68b92a3908..6e89acb959 100644
--- a/tests/test_column_types.py
+++ b/tests/test_column_types.py
@@ -933,9 +933,7 @@ async def test_set_column_type_ui_data_includes_applicable_types(
     await ds_ct_editor_permission.invoke_startup()
     response = await ds_ct_editor_permission.client.get(
         "/data/posts",
-        cookies={
-            "ds_actor": ds_ct_editor_permission.client.actor_cookie({"id": "editor"})
-        },
+        actor={"id": "editor"},
     )
     assert response.status_code == 200
     data = _window_data_from_html(response.text, "_setColumnTypeData")
diff --git a/tests/test_html.py b/tests/test_html.py
index 4fc144ab34..e38898da7a 100644
--- a/tests/test_html.py
+++ b/tests/test_html.py
@@ -1003,10 +1003,10 @@ async def test_navigation_menu_links(
     # Enable root user if testing with root actor
     if actor_id == "root":
         ds_client.ds.root_enabled = True
-    cookies = {}
+    kwargs = {}
     if actor_id:
-        cookies = {"ds_actor": ds_client.actor_cookie({"id": actor_id})}
-    html = (await ds_client.get("/", cookies=cookies)).text
+        kwargs["actor"] = {"id": actor_id}
+    html = (await ds_client.get("/", **kwargs)).text
     soup = Soup(html, "html.parser")
     details = soup.find("nav").find("details")
     if not actor_id:
@@ -1215,8 +1215,7 @@ async def test_actions_page(ds_client):
     original_root_enabled = ds_client.ds.root_enabled
     try:
         ds_client.ds.root_enabled = True
-        cookies = {"ds_actor": ds_client.actor_cookie({"id": "root"})}
-        response = await ds_client.get("/-/actions", cookies=cookies)
+        response = await ds_client.get("/-/actions", actor={"id": "root"})
         assert response.status_code == 200
         assert "Registered actions" in response.text
         assert "<th>Name</th>" in response.text
@@ -1233,8 +1232,7 @@ async def test_actions_page_does_not_display_none_string(ds_client):
     original_root_enabled = ds_client.ds.root_enabled
     try:
         ds_client.ds.root_enabled = True
-        cookies = {"ds_actor": ds_client.actor_cookie({"id": "root"})}
-        response = await ds_client.get("/-/actions", cookies=cookies)
+        response = await ds_client.get("/-/actions", actor={"id": "root"})
         assert response.status_code == 200
         assert "<code>None</code>" not in response.text
     finally:
@@ -1247,11 +1245,11 @@ async def test_permission_debug_tabs_with_query_string(ds_client):
     original_root_enabled = ds_client.ds.root_enabled
     try:
         ds_client.ds.root_enabled = True
-        cookies = {"ds_actor": ds_client.actor_cookie({"id": "root"})}
+        actor = {"id": "root"}
 
         # Test /-/allowed with query string
         response = await ds_client.get(
-            "/-/allowed?action=view-table&page_size=50", cookies=cookies
+            "/-/allowed?action=view-table&page_size=50", actor=actor
         )
         assert response.status_code == 200
         # Check that Rules and Check tabs have the query string
@@ -1263,7 +1261,7 @@ async def test_permission_debug_tabs_with_query_string(ds_client):
 
         # Test /-/rules with query string
         response = await ds_client.get(
-            "/-/rules?action=view-database&parent=test", cookies=cookies
+            "/-/rules?action=view-database&parent=test", actor=actor
         )
         assert response.status_code == 200
         # Check that Allowed and Check tabs have the query string
@@ -1271,7 +1269,7 @@ async def test_permission_debug_tabs_with_query_string(ds_client):
         assert 'href="/-/check?action=view-database&amp;parent=test"' in response.text
 
         # Test /-/check with query string
-        response = await ds_client.get("/-/check?action=execute-sql", cookies=cookies)
+        response = await ds_client.get("/-/check?action=execute-sql", actor=actor)
         assert response.status_code == 200
         # Check that Allowed and Rules tabs have the query string
         assert 'href="/-/allowed?action=execute-sql"' in response.text
diff --git a/tests/test_internals_datasette_client.py b/tests/test_internals_datasette_client.py
index 326fcdc0e1..ccac280b93 100644
--- a/tests/test_internals_datasette_client.py
+++ b/tests/test_internals_datasette_client.py
@@ -311,3 +311,76 @@ async def test_view(datasette):
         assert all(in_client_values), f"Expected all True, got {in_client_values}"
     finally:
         ds.pm.unregister(name="test_in_client_skip_plugin")
+
+
+@pytest.mark.asyncio
+async def test_actor_parameter_sets_cookie(datasette):
+    """Passing actor= should sign a ds_actor cookie and authenticate the request."""
+    response = await datasette.client.get("/-/actor.json", actor={"id": "root"})
+    assert response.status_code == 200
+    assert response.json() == {"actor": {"id": "root"}}
+
+
+@pytest.mark.asyncio
+async def test_actor_parameter_works_with_request_method(datasette):
+    response = await datasette.client.request(
+        "GET", "/-/actor.json", actor={"id": "root"}
+    )
+    assert response.status_code == 200
+    assert response.json() == {"actor": {"id": "root"}}
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    "method", ["get", "post", "options", "head", "put", "patch", "delete"]
+)
+async def test_actor_parameter_all_http_methods(datasette, method):
+    """actor= should not cause errors on any HTTP verb wrapper."""
+    client_method = getattr(datasette.client, method)
+    # Just verify no TypeError about unexpected 'actor' kwarg
+    response = await client_method("/", actor={"id": "root"})
+    assert isinstance(response, httpx.Response)
+
+
+@pytest.mark.asyncio
+async def test_actor_parameter_conflicts_with_ds_actor_cookie(datasette):
+    """Passing both actor= and a ds_actor cookie should raise TypeError."""
+    with pytest.raises(TypeError, match="actor"):
+        await datasette.client.get(
+            "/-/actor.json",
+            actor={"id": "root"},
+            cookies={"ds_actor": datasette.client.actor_cookie({"id": "other"})},
+        )
+
+
+@pytest.mark.asyncio
+async def test_actor_parameter_merges_with_other_cookies(datasette):
+    """actor= should coexist with unrelated cookies."""
+    response = await datasette.client.get(
+        "/-/actor.json",
+        actor={"id": "root"},
+        cookies={"unrelated": "value"},
+    )
+    assert response.status_code == 200
+    assert response.json() == {"actor": {"id": "root"}}
+
+
+@pytest.mark.asyncio
+async def test_actor_parameter_with_skip_permission_checks(
+    datasette_with_permissions,
+):
+    """actor= should be compatible with skip_permission_checks."""
+    ds = datasette_with_permissions
+    # Non-admin actor with skip_permission_checks=True should get 200
+    response = await ds.client.get(
+        "/test_db.json",
+        actor={"id": "user"},
+        skip_permission_checks=True,
+    )
+    assert response.status_code == 200
+    # Admin actor on its own should also get 200
+    response = await ds.client.get("/test_db.json", actor={"id": "admin"})
+    assert response.status_code == 200
+    # Non-admin actor should get 403
+    response = await ds.client.get("/test_db.json", actor={"id": "user"})
+    assert response.status_code == 403
diff --git a/tests/test_permission_endpoints.py b/tests/test_permission_endpoints.py
index 84f3370fb6..e25be23ec3 100644
--- a/tests/test_permission_endpoints.py
+++ b/tests/test_permission_endpoints.py
@@ -117,9 +117,7 @@ async def test_allowed_json_with_actor(ds_with_permissions):
     """Test /-/allowed.json includes actor information."""
     response = await ds_with_permissions.client.get(
         "/-/allowed.json?action=view-table",
-        cookies={
-            "ds_actor": ds_with_permissions.client.actor_cookie({"id": "test_user"})
-        },
+        actor={"id": "test_user"},
     )
     assert response.status_code == 200
     data = response.json()
@@ -252,7 +250,7 @@ async def test_rules_json_basic(
     # Use root actor for rules endpoint (requires permissions-debug)
     response = await ds_with_permissions.client.get(
         path,
-        cookies={"ds_actor": ds_with_permissions.client.actor_cookie({"id": "root"})},
+        actor={"id": "root"},
     )
     assert response.status_code == expected_status
     data = response.json()
@@ -264,7 +262,7 @@ async def test_rules_json_response_structure(ds_with_permissions):
     """Test that /-/rules.json returns the expected structure."""
     response = await ds_with_permissions.client.get(
         "/-/rules.json?action=view-instance",
-        cookies={"ds_actor": ds_with_permissions.client.actor_cookie({"id": "root"})},
+        actor={"id": "root"},
     )
     assert response.status_code == 200
     data = response.json()
@@ -294,7 +292,7 @@ async def test_rules_json_includes_all_rules(ds_with_permissions):
     # Root user should see rules for everything
     response = await ds_with_permissions.client.get(
         "/-/rules.json?action=view-table",
-        cookies={"ds_actor": ds_with_permissions.client.actor_cookie({"id": "root"})},
+        actor={"id": "root"},
     )
     assert response.status_code == 200
     data = response.json()
@@ -326,7 +324,7 @@ async def test_rules_json_pagination():
     # Test basic pagination structure - just verify it returns paginated results
     response = await ds.client.get(
         "/-/rules.json?action=view-table&page_size=2&page=1",
-        cookies={"ds_actor": ds.client.actor_cookie({"id": "root"})},
+        actor={"id": "root"},
     )
     assert response.status_code == 200
     data = response.json()
@@ -343,7 +341,7 @@ async def test_rules_json_with_actor(ds_with_permissions):
     # Use root actor (rules endpoint requires permissions-debug)
     response = await ds_with_permissions.client.get(
         "/-/rules.json?action=view-table",
-        cookies={"ds_actor": ds_with_permissions.client.actor_cookie({"id": "root"})},
+        actor={"id": "root"},
     )
     assert response.status_code == 200
     data = response.json()
@@ -374,7 +372,7 @@ async def test_root_user_respects_settings_deny():
     # Root user should NOT see the denied database
     response = await ds.client.get(
         "/-/allowed.json?action=view-database",
-        cookies={"ds_actor": ds.client.actor_cookie({"id": "root"})},
+        actor={"id": "root"},
     )
     assert response.status_code == 200
     data = response.json()
@@ -415,7 +413,7 @@ async def test_root_user_respects_settings_deny_tables():
     # Root user should NOT see tables from the content database
     response = await ds.client.get(
         "/-/allowed.json?action=view-table",
-        cookies={"ds_actor": ds.client.actor_cookie({"id": "root"})},
+        actor={"id": "root"},
     )
     assert response.status_code == 200
     data = response.json()
@@ -475,7 +473,7 @@ def permission_resources_sql(self, datasette, actor, action):
         # User should NOT have execute-sql permission because view-database is denied
         response = await ds.client.get(
             "/-/allowed.json?action=execute-sql",
-            cookies={"ds_actor": ds.client.actor_cookie({"id": "test_user"})},
+            actor={"id": "test_user"},
         )
         assert response.status_code == 200
         data = response.json()
@@ -491,7 +489,7 @@ def permission_resources_sql(self, datasette, actor, action):
         # (may be 403 or 302 redirect to login/error page depending on middleware)
         response = await ds.client.get(
             "/secret?sql=SELECT+1",
-            cookies={"ds_actor": ds.client.actor_cookie({"id": "test_user"})},
+            actor={"id": "test_user"},
         )
         assert response.status_code in (302, 403), (
             f"Expected 302 or 403 when trying to execute SQL without view-database permission, "
diff --git a/tests/test_permissions.py b/tests/test_permissions.py
index 04195f75f4..0c09e77349 100644
--- a/tests/test_permissions.py
+++ b/tests/test_permissions.py
@@ -1171,10 +1171,10 @@ async def test_api_explorer_visibility(
     try:
         prev_config = perms_ds.config
         perms_ds.config = config or {}
-        cookies = {}
+        kwargs = {}
         if is_logged_in:
-            cookies = {"ds_actor": perms_ds.client.actor_cookie({"id": "user"})}
-        response = await perms_ds.client.get("/-/api", cookies=cookies)
+            kwargs["actor"] = {"id": "user"}
+        response = await perms_ds.client.get("/-/api", **kwargs)
         if expected_visible_tables:
             assert response.status_code == 200
             # Search HTML for stuff matching:
@@ -1208,8 +1208,7 @@ async def test_view_table_token_cannot_gain_access_without_base_permission(perms
             # Restricted token claims access to perms_ds_two/t1 only
             "_r": {"r": {"perms_ds_two": {"t1": ["vt"]}}},
         }
-        cookies = {"ds_actor": perms_ds.client.actor_cookie(actor)}
-        response = await perms_ds.client.get("/perms_ds_two/t1.json", cookies=cookies)
+        response = await perms_ds.client.get("/perms_ds_two/t1.json", actor=actor)
         assert response.status_code == 403
     finally:
         perms_ds.config = previous_config
@@ -1328,7 +1327,7 @@ async def test_actor_restrictions(
     if restrictions:
         actor["_r"] = restrictions
     method = getattr(perms_ds.client, verb)
-    kwargs = {"cookies": {"ds_actor": perms_ds.client.actor_cookie(actor)}}
+    kwargs = {"actor": actor}
     if body:
         kwargs["json"] = body
     perms_ds._permission_checks.clear()
@@ -1459,7 +1458,7 @@ async def test_actor_restrictions_do_not_expand_allowed_resources(perms_ds):
         # And explicit permission checks should still deny
         response = await perms_ds.client.get(
             "/perms_ds_one/t1.json",
-            cookies={"ds_actor": perms_ds.client.actor_cookie(actor)},
+            actor=actor,
         )
         assert response.status_code == 403
     finally:
@@ -1527,18 +1526,17 @@ async def test_actor_restrictions_json_endpoints_show_filtered_listings(perms_ds
     """Test that /.json and /db.json show correct filtered listings - issue #2534"""
 
     actor = {"id": "user", "_r": {"r": {"perms_ds_one": {"t1": ["vt"]}}}}
-    cookies = {"ds_actor": perms_ds.client.actor_cookie(actor)}
 
     # /.json should be 403 (no view-instance permission)
-    response = await perms_ds.client.get("/.json", cookies=cookies)
+    response = await perms_ds.client.get("/.json", actor=actor)
     assert response.status_code == 403
 
     # /perms_ds_one.json should be 403 (no view-database permission)
-    response = await perms_ds.client.get("/perms_ds_one.json", cookies=cookies)
+    response = await perms_ds.client.get("/perms_ds_one.json", actor=actor)
     assert response.status_code == 403
 
     # /perms_ds_one/t1.json should be 200
-    response = await perms_ds.client.get("/perms_ds_one/t1.json", cookies=cookies)
+    response = await perms_ds.client.get("/perms_ds_one/t1.json", actor=actor)
     assert response.status_code == 200
 
 
@@ -1547,10 +1545,9 @@ async def test_actor_restrictions_view_instance_only(perms_ds):
     """Test actor restricted to view-instance only - issue #2534"""
 
     actor = {"id": "user", "_r": {"a": ["vi"]}}
-    cookies = {"ds_actor": perms_ds.client.actor_cookie(actor)}
 
     # /.json should be 200 (has view-instance permission)
-    response = await perms_ds.client.get("/.json", cookies=cookies)
+    response = await perms_ds.client.get("/.json", actor=actor)
     assert response.status_code == 200
 
     # But no databases should be visible (no view-database permission)
diff --git a/tests/test_plugins.py b/tests/test_plugins.py
index c9de1c5728..083e23a01f 100644
--- a/tests/test_plugins.py
+++ b/tests/test_plugins.py
@@ -1024,7 +1024,7 @@ async def test_hook_view_actions(ds_client):
     assert get_actions_links(response.text) == []
     response_2 = await ds_client.get(
         "/fixtures/simple_view",
-        cookies={"ds_actor": ds_client.actor_cookie({"id": "bob"})},
+        actor={"id": "bob"},
     )
     assert ">View actions<" in response_2.text
     assert sorted(
@@ -1088,7 +1088,7 @@ async def test_hook_row_actions(ds_client):
 
     response_2 = await ds_client.get(
         "/fixtures/facet_cities/1",
-        cookies={"ds_actor": ds_client.actor_cookie({"id": "sam"})},
+        actor={"id": "sam"},
     )
     assert get_actions_links(response_2.text) == [
         {
@@ -1116,9 +1116,7 @@ async def test_hook_homepage_actions(ds_client):
     # No button for anonymous users
     assert "<span>Homepage actions</span>" not in response.text
     # Signed in user gets an action
-    response2 = await ds_client.get(
-        "/", cookies={"ds_actor": ds_client.actor_cookie({"id": "troy"})}
-    )
+    response2 = await ds_client.get("/", actor={"id": "troy"})
     assert "<span>Homepage actions</span>" in response2.text
     assert get_actions_links(response2.text) == [
         {
diff --git a/tests/test_schema_endpoints.py b/tests/test_schema_endpoints.py
index 50742df2cd..c95d8614f6 100644
--- a/tests/test_schema_endpoints.py
+++ b/tests/test_schema_endpoints.py
@@ -151,7 +151,7 @@ async def test_schema_permission_enforcement(schema_ds, url):
     # Authenticated user with permission should succeed
     response = await schema_ds.client.get(
         url,
-        cookies={"ds_actor": schema_ds.client.actor_cookie({"id": "root"})},
+        actor={"id": "root"},
     )
     assert response.status_code == 200
 
@@ -171,7 +171,7 @@ async def test_instance_schema_respects_database_permissions(schema_ds):
     # Authenticated user should see all databases
     response = await schema_ds.client.get(
         "/-/schema.json",
-        cookies={"ds_actor": schema_ds.client.actor_cookie({"id": "root"})},
+        actor={"id": "root"},
     )
     assert response.status_code == 200
     data = response.json()
diff --git a/tests/test_search_tables.py b/tests/test_search_tables.py
index 34b377067d..b901c0b370 100644
--- a/tests/test_search_tables.py
+++ b/tests/test_search_tables.py
@@ -86,7 +86,7 @@ async def test_tables_search_with_auth(ds_with_tables):
     # Editor user should see content.articles
     response = await ds_with_tables.client.get(
         "/-/tables.json?q=articles",
-        cookies={"ds_actor": ds_with_tables.client.actor_cookie({"id": "editor"})},
+        actor={"id": "editor"},
     )
     assert response.status_code == 200
     data = response.json()
@@ -104,7 +104,7 @@ async def test_tables_search_partial_match(ds_with_tables):
     # Search for "com" should match "comments"
     response = await ds_with_tables.client.get(
         "/-/tables.json?q=com",
-        cookies={"ds_actor": ds_with_tables.client.actor_cookie({"id": "user"})},
+        actor={"id": "user"},
     )
     assert response.status_code == 200
     data = response.json()
@@ -120,7 +120,7 @@ async def test_tables_search_respects_database_permissions(ds_with_tables):
     # Even authenticated users shouldn't see it because database is denied
     response = await ds_with_tables.client.get(
         "/-/tables.json?q=secrets",
-        cookies={"ds_actor": ds_with_tables.client.actor_cookie({"id": "user"})},
+        actor={"id": "user"},
     )
     assert response.status_code == 200
     data = response.json()
@@ -135,7 +135,7 @@ async def test_tables_search_respects_table_permissions(ds_with_tables):
     # Regular authenticated user searching for "users"
     response = await ds_with_tables.client.get(
         "/-/tables.json?q=users",
-        cookies={"ds_actor": ds_with_tables.client.actor_cookie({"id": "regular"})},
+        actor={"id": "regular"},
     )
     assert response.status_code == 200
     data = response.json()
@@ -150,7 +150,7 @@ async def test_tables_search_response_structure(ds_with_tables):
     """Test that response has correct structure."""
     response = await ds_with_tables.client.get(
         "/-/tables.json?q=users",
-        cookies={"ds_actor": ds_with_tables.client.actor_cookie({"id": "user"})},
+        actor={"id": "user"},
     )
     assert response.status_code == 200
     data = response.json()