diff --git a/Modules/Core/Transform/include/itkKernelTransform.h b/Modules/Core/Transform/include/itkKernelTransform.h
index 71d61e84980..c00deba14d3 100644
--- a/Modules/Core/Transform/include/itkKernelTransform.h
+++ b/Modules/Core/Transform/include/itkKernelTransform.h
@@ -375,7 +375,7 @@ class ITK_TEMPLATE_EXPORT KernelTransform : public Transform<TParametersValueTyp
   bool m_WMatrixComputed{};
 
   /** Identity matrix. */
-  IMatrixType m_I;
+  IMatrixType m_I{};
 
   /** The list of source landmarks, denoted 'p'. */
   PointSetPointer m_SourceLandmarks{};
diff --git a/Modules/Filtering/AnisotropicSmoothing/include/itkCurvatureNDAnisotropicDiffusionFunction.h b/Modules/Filtering/AnisotropicSmoothing/include/itkCurvatureNDAnisotropicDiffusionFunction.h
index 4877dd09040..ba3e457b700 100644
--- a/Modules/Filtering/AnisotropicSmoothing/include/itkCurvatureNDAnisotropicDiffusionFunction.h
+++ b/Modules/Filtering/AnisotropicSmoothing/include/itkCurvatureNDAnisotropicDiffusionFunction.h
@@ -133,7 +133,7 @@ class ITK_TEMPLATE_EXPORT CurvatureNDAnisotropicDiffusionFunction : public Scala
   DerivativeOperator<PixelType, Self::ImageDimension> m_DerivativeOperator{};
 
   /** Modified global average gradient magnitude term. */
-  PixelType m_K;
+  PixelType m_K{};
 
   /** */
   static double m_MIN_NORM;
diff --git a/Modules/Filtering/AnisotropicSmoothing/include/itkGradientNDAnisotropicDiffusionFunction.h b/Modules/Filtering/AnisotropicSmoothing/include/itkGradientNDAnisotropicDiffusionFunction.h
index 2df1c376581..df17c699610 100644
--- a/Modules/Filtering/AnisotropicSmoothing/include/itkGradientNDAnisotropicDiffusionFunction.h
+++ b/Modules/Filtering/AnisotropicSmoothing/include/itkGradientNDAnisotropicDiffusionFunction.h
@@ -119,7 +119,7 @@ class ITK_TEMPLATE_EXPORT GradientNDAnisotropicDiffusionFunction : public Scalar
   DerivativeOperator<PixelType, Self::ImageDimension> m_DerivativeOperator{};
 
   /** Modified global average gradient magnitude term. */
-  PixelType m_K;
+  PixelType m_K{};
 
   NeighborhoodSizeValueType m_Center{};
   NeighborhoodSizeValueType m_Stride[ImageDimension]{};
diff --git a/Modules/Filtering/AnisotropicSmoothing/include/itkVectorGradientNDAnisotropicDiffusionFunction.h b/Modules/Filtering/AnisotropicSmoothing/include/itkVectorGradientNDAnisotropicDiffusionFunction.h
index 3d35907d27b..26be0ffe0ee 100644
--- a/Modules/Filtering/AnisotropicSmoothing/include/itkVectorGradientNDAnisotropicDiffusionFunction.h
+++ b/Modules/Filtering/AnisotropicSmoothing/include/itkVectorGradientNDAnisotropicDiffusionFunction.h
@@ -105,7 +105,7 @@ class ITK_TEMPLATE_EXPORT VectorGradientNDAnisotropicDiffusionFunction
   DerivativeOperator<ScalarValueType, Self::ImageDimension> m_DerivativeOperator{};
 
   /** Modified global average gradient magnitude term. */
-  ScalarValueType m_K;
+  ScalarValueType m_K{};
 
   static double m_MIN_NORM;
 
diff --git a/Modules/Filtering/GPUAnisotropicSmoothing/include/itkGPUGradientNDAnisotropicDiffusionFunction.h b/Modules/Filtering/GPUAnisotropicSmoothing/include/itkGPUGradientNDAnisotropicDiffusionFunction.h
index 156d4d5a2a6..9a8179ce917 100644
--- a/Modules/Filtering/GPUAnisotropicSmoothing/include/itkGPUGradientNDAnisotropicDiffusionFunction.h
+++ b/Modules/Filtering/GPUAnisotropicSmoothing/include/itkGPUGradientNDAnisotropicDiffusionFunction.h
@@ -120,7 +120,7 @@ class ITK_TEMPLATE_EXPORT GPUGradientNDAnisotropicDiffusionFunction
   DerivativeOperator<PixelType, Self::ImageDimension> m_DerivativeOperator{};
 
   /** Modified global average gradient magnitude term. */
-  PixelType m_K;
+  PixelType m_K{};
 
   NeighborhoodSizeValueType m_Center{};
   NeighborhoodSizeValueType m_Stride[ImageDimension]{};
diff --git a/Modules/Numerics/Optimizers/include/itkSPSAOptimizer.h b/Modules/Numerics/Optimizers/include/itkSPSAOptimizer.h
index 958cfad9584..ab7bd753da8 100644
--- a/Modules/Numerics/Optimizers/include/itkSPSAOptimizer.h
+++ b/Modules/Numerics/Optimizers/include/itkSPSAOptimizer.h
@@ -320,7 +320,7 @@ class ITKOptimizers_EXPORT SPSAOptimizer : public SingleValuedNonLinearOptimizer
   /** Parameters, as described by Spall.*/
   double m_Sa{};
   double m_Sc{};
-  double m_A;
+  double m_A{};
   double m_Alpha{};
   double m_Gamma{};
 }; // end class SPSAOptimizer
diff --git a/Modules/Numerics/Optimizers/test/itkParticleSwarmOptimizerTestFunctions.h b/Modules/Numerics/Optimizers/test/itkParticleSwarmOptimizerTestFunctions.h
index e8627dd5fb2..381e113b61e 100644
--- a/Modules/Numerics/Optimizers/test/itkParticleSwarmOptimizerTestFunctions.h
+++ b/Modules/Numerics/Optimizers/test/itkParticleSwarmOptimizerTestFunctions.h
@@ -141,7 +141,7 @@ class ParticleSwarmTestF2 : public SingleValuedCostFunction
   }
 
 private:
-  MatrixType m_A;
+  MatrixType m_A{};
   VectorType m_Intercept{};
 };
 
diff --git a/Modules/Registration/FEM/include/itkFEMRegistrationFilter.h b/Modules/Registration/FEM/include/itkFEMRegistrationFilter.h
index 6bb3993b6e6..4c3aabef9a3 100644
--- a/Modules/Registration/FEM/include/itkFEMRegistrationFilter.h
+++ b/Modules/Registration/FEM/include/itkFEMRegistrationFilter.h
@@ -683,7 +683,7 @@ class ITK_TEMPLATE_EXPORT FEMRegistrationFilter : public ImageToImageFilter<TMov
   vnl_vector<unsigned int> m_MeshPixelsPerElementAtEachResolution{};
 
   Float             m_TimeStep{ 1 };
-  vnl_vector<Float> m_E;
+  vnl_vector<Float> m_E{};
   vnl_vector<Float> m_Rho{};
   vnl_vector<Float> m_Gamma{};
   Float             m_Energy{ 0.0 };      // current value of energy