diff --git a/Examples/GUI/Win32/SampleMFC/SampleDoc.h b/Examples/GUI/Win32/SampleMFC/SampleDoc.h
index efdb06fd01b..d28f7436b16 100644
--- a/Examples/GUI/Win32/SampleMFC/SampleDoc.h
+++ b/Examples/GUI/Win32/SampleMFC/SampleDoc.h
@@ -44,7 +44,7 @@ class CSampleDoc : public vtkMFCDocument
         //{{AFX_VIRTUAL(CSampleDoc)
         public:
         virtual BOOL OnNewDocument();
-        virtual void Serialize(CArchive& ar);
+        void Serialize(CArchive& ar) override;
         virtual BOOL OnOpenDocument(LPCTSTR lpszPathName);
         //}}AFX_VIRTUAL
 
diff --git a/Examples/GUI/Win32/SampleMFC/vtkMFCRenderView.h b/Examples/GUI/Win32/SampleMFC/vtkMFCRenderView.h
index dea078cfa01..80bd96dc566 100644
--- a/Examples/GUI/Win32/SampleMFC/vtkMFCRenderView.h
+++ b/Examples/GUI/Win32/SampleMFC/vtkMFCRenderView.h
@@ -46,28 +46,28 @@ class vtkMFCRenderView : public vtkMFCView
   virtual void OnInitialUpdate();
   virtual LRESULT WindowProc(UINT message, WPARAM wParam, LPARAM lParam);
   void Render() {this->RenderWindow->Render();};
-  vtkWindow *GetVTKWindow() {return this->RenderWindow;};
-  virtual void SetupMemoryRendering(int x, int y, HDC prn) {
+  vtkWindow *GetVTKWindow() override {return this->RenderWindow;};
+  void SetupMemoryRendering(int x, int y, HDC prn) override {
     this->RenderWindow->SetupMemoryRendering(x,y,prn);};
-  virtual void ResumeScreenRendering() {
+  void ResumeScreenRendering() override {
     this->RenderWindow->ResumeScreenRendering();};
-  virtual unsigned char *GetMemoryData() {
+  unsigned char *GetMemoryData() override {
     return this->RenderWindow->GetMemoryData();};
 
   // Overrides
   // ClassWizard generated virtual function overrides
   //{{AFX_VIRTUAL(vtkMFCRenderView)
 protected:
-  virtual void OnDraw(CDC* pDC);      // overridden to draw this view
-  virtual BOOL OnPreparePrinting(CPrintInfo* pInfo);
+  void OnDraw(CDC* pDC) override;      // overridden to draw this view
+  BOOL OnPreparePrinting(CPrintInfo* pInfo) override;
   //}}AFX_VIRTUAL
 
   // Implementation
 protected:
   virtual ~vtkMFCRenderView();
 #ifdef _DEBUG
-  virtual void AssertValid() const;
-  virtual void Dump(CDumpContext& dc) const;
+  void AssertValid() const override;
+  void Dump(CDumpContext& dc) const override;
 #endif
 
   // Generated message map functions
diff --git a/IO/ADIOS/ADIOSWriter.cxx b/IO/ADIOS/ADIOSWriter.cxx
index 8f81e7a8763..88d1690f48b 100644
--- a/IO/ADIOS/ADIOSWriter.cxx
+++ b/IO/ADIOS/ADIOSWriter.cxx
@@ -156,7 +156,7 @@ struct Writer::WriterImpl
     { }
 
     virtual ~ScalarValueT() { }
-    virtual uint64_t GetInt() { return static_cast<uint64_t>(this->ValueT); }
+    uint64_t GetInt() override { return static_cast<uint64_t>(this->ValueT); }
 
     const T ValueT;
   };
diff --git a/IO/ADIOS/FunctionPointers.h b/IO/ADIOS/FunctionPointers.h
index 34d8692c548..b2cd222e624 100644
--- a/IO/ADIOS/FunctionPointers.h
+++ b/IO/ADIOS/FunctionPointers.h
@@ -28,7 +28,7 @@ class Functor0Args : public BaseFunctor
 {
 public:
   virtual ~Functor0Args() { }
-  virtual void ExecVoid()
+  void ExecVoid() override
   {
     (*this)();
   }
@@ -47,7 +47,7 @@ class MemberFunction0Args : public Functor0Args<TReturn>
 
   virtual ~MemberFunction0Args() { }
 
-  virtual TReturn operator() ()
+  TReturn operator() () override
   { return (this->Instance->*this->FunctionPtr)(); }
 
 private:
@@ -66,7 +66,7 @@ class MemberFunction1Arg : public Functor0Args<TReturn>
 
   virtual ~MemberFunction1Arg() { }
 
-  virtual TReturn operator() ()
+  TReturn operator() () override
   { return (this->Instance->*this->FunctionPtr)(this->Arg1); }
 
 private:
@@ -87,7 +87,7 @@ class MemberFunction2Args : public Functor0Args<TReturn>
 
   virtual ~MemberFunction2Args() { }
 
-  virtual TReturn operator() ()
+  TReturn operator() () override
   { return (this->Instance->*this->FunctionPtr)(this->Arg1, this->Arg2); }
 
 private:
diff --git a/IO/Video/vtkMILVideoSource.h b/IO/Video/vtkMILVideoSource.h
index 1bd6125f883..32458c10cd5 100644
--- a/IO/Video/vtkMILVideoSource.h
+++ b/IO/Video/vtkMILVideoSource.h
@@ -76,32 +76,32 @@ class VTKIOVIDEO_EXPORT vtkMILVideoSource : public vtkVideoSource
   /**
    * Standard VCR functionality: Record incoming video.
    */
-  void Record();
+  void Record() override;
 
   /**
    * Standard VCR functionality: Play recorded video.
    */
-  void Play();
+  void Play() override;
 
   /**
    * Standard VCR functionality: Stop recording or playing.
    */
-  void Stop();
+  void Stop() override;
 
   /**
    * Grab a single video frame.
    */
-  void Grab();
+  void Grab() override;
 
   /**
    * Request a particular frame size (set the third value to 1).
    */
-  void SetFrameSize(int x, int y, int z);
+  void SetFrameSize(int x, int y, int z) override;
 
   /**
    * Request a particular output format (default: VTK_RGB).
    */
-  void SetOutputFormat(int format);
+  void SetOutputFormat(int format) override;
 
   //@{
   /**
@@ -240,13 +240,13 @@ class VTKIOVIDEO_EXPORT vtkMILVideoSource : public vtkVideoSource
    * Initialize the driver (this is called automatically when the
    * first grab is done).
    */
-  void Initialize();
+  void Initialize() override;
 
   /**
    * Free the driver (this is called automatically inside the
    * destructor).
    */
-  void ReleaseSystemResources();
+  void ReleaseSystemResources() override;
 
   //@{
   /**
@@ -256,7 +256,7 @@ class VTKIOVIDEO_EXPORT vtkMILVideoSource : public vtkVideoSource
   void *OldUserDataPtr;
   int FrameCounter;
   int ForceGrab;
-  void InternalGrab();
+  void InternalGrab() override;
   //@}
 
 protected:
diff --git a/Interaction/Widgets/vtkXYPlotRepresentation.h b/Interaction/Widgets/vtkXYPlotRepresentation.h
index 22d4a9906f5..7b5b56ef9a1 100644
--- a/Interaction/Widgets/vtkXYPlotRepresentation.h
+++ b/Interaction/Widgets/vtkXYPlotRepresentation.h
@@ -57,9 +57,9 @@ class VTKINTERACTIONWIDGETS_EXPORT vtkXYPlotRepresentation : public vtkBorderRep
   /**
    * Satisfy the superclass' API.
    */
-  virtual void BuildRepresentation();
-  virtual void WidgetInteraction(double eventPos[2]);
-  virtual void GetSize(double size[2])
+  void BuildRepresentation() override;
+  void WidgetInteraction(double eventPos[2]) override;
+  void GetSize(double size[2]) override
     {size[0]=2.0; size[1]=2.0;}
   //@}
 
diff --git a/Rendering/OpenGL2/vtkEGLRenderWindow.h b/Rendering/OpenGL2/vtkEGLRenderWindow.h
index 74f12dcbc99..e816e5cd643 100644
--- a/Rendering/OpenGL2/vtkEGLRenderWindow.h
+++ b/Rendering/OpenGL2/vtkEGLRenderWindow.h
@@ -65,7 +65,7 @@ class VTKRENDERINGOPENGL2_EXPORT vtkEGLRenderWindow : public vtkOpenGLRenderWind
    * should be possible to call them multiple times, even changing WindowId
    * in-between.  This is what WindowRemap does.
    */
-  virtual void Initialize(void);
+  void Initialize(void) override;
 
   /**
    * "Deinitialize" the rendering window.  This will shutdown all system-specific
@@ -203,7 +203,7 @@ class VTKRENDERINGOPENGL2_EXPORT vtkEGLRenderWindow : public vtkOpenGLRenderWind
    * because point sprites don't work correctly (gl_PointCoord is undefined) unless
    * glEnable(GL_POINT_SPRITE)
    */
-  virtual bool IsPointSpriteBugPresent();
+  bool IsPointSpriteBugPresent() override;
 
 protected:
   vtkEGLRenderWindow();
@@ -216,8 +216,8 @@ class VTKRENDERINGOPENGL2_EXPORT vtkEGLRenderWindow : public vtkOpenGLRenderWind
   class vtkInternals;
   vtkInternals* Internals;
 
-  void CreateAWindow();
-  void DestroyWindow();
+  void CreateAWindow() override;
+  void DestroyWindow() override;
   void ResizeWindow(int width, int height);
 
   /**
diff --git a/Rendering/OpenGL2/vtkOSOpenGLRenderWindow.h b/Rendering/OpenGL2/vtkOSOpenGLRenderWindow.h
index 87672614b86..75c56995553 100644
--- a/Rendering/OpenGL2/vtkOSOpenGLRenderWindow.h
+++ b/Rendering/OpenGL2/vtkOSOpenGLRenderWindow.h
@@ -63,7 +63,7 @@ class VTKRENDERINGOPENGL2_EXPORT vtkOSOpenGLRenderWindow : public vtkOpenGLRende
    * should be possible to call them multiple times, even changing WindowId
    * in-between.  This is what WindowRemap does.
    */
-  virtual void Initialize(void);
+  void Initialize(void) override;
 
   /**
    * "Deinitialize" the rendering window.  This will shutdown all system-specific
@@ -235,8 +235,8 @@ class VTKRENDERINGOPENGL2_EXPORT vtkOSOpenGLRenderWindow : public vtkOpenGLRende
   int      CursorHidden;
   int      ForceMakeCurrent;
 
-  void CreateAWindow();
-  void DestroyWindow();
+  void CreateAWindow() override;
+  void DestroyWindow() override;
   void CreateOffScreenWindow(int width, int height);
   void DestroyOffScreenWindow();
   void ResizeOffScreenWindow(int width, int height);
diff --git a/Rendering/OpenVR/vtkOpenVRDefaultOverlay.h b/Rendering/OpenVR/vtkOpenVRDefaultOverlay.h
index 54e364c4d4e..380a4d4b4c3 100644
--- a/Rendering/OpenVR/vtkOpenVRDefaultOverlay.h
+++ b/Rendering/OpenVR/vtkOpenVRDefaultOverlay.h
@@ -34,13 +34,13 @@ class VTKRENDERINGOPENVR_EXPORT vtkOpenVRDefaultOverlay : public vtkOpenVROverla
   /**
    * Render the overlay, we set some opf the spots based on current settings
    */
-  virtual void Render();
+  void Render() override;
 
 protected:
   vtkOpenVRDefaultOverlay();
   ~vtkOpenVRDefaultOverlay();
 
-  virtual void SetupSpots();
+  void SetupSpots() override;
 
 private:
   vtkOpenVRDefaultOverlay(const vtkOpenVRDefaultOverlay&) = delete;
diff --git a/Rendering/OptiX/vtkOptiXCompositePolyDataMapper2Node.h b/Rendering/OptiX/vtkOptiXCompositePolyDataMapper2Node.h
index 6c0971fb525..abda8e60768 100644
--- a/Rendering/OptiX/vtkOptiXCompositePolyDataMapper2Node.h
+++ b/Rendering/OptiX/vtkOptiXCompositePolyDataMapper2Node.h
@@ -42,7 +42,7 @@ class VTKRENDERINGOPTIX_EXPORT vtkOptiXCompositePolyDataMapper2Node :
   /**
    * Make OptiX calls for rendering.
    */
-  virtual void Render(bool prepass);
+  void Render(bool prepass) override;
 
 protected:
   vtkOptiXCompositePolyDataMapper2Node();
diff --git a/Utilities/Benchmarks/GLBenchmarking.cxx b/Utilities/Benchmarks/GLBenchmarking.cxx
index 8d5c26887d4..40d401f47ce 100644
--- a/Utilities/Benchmarks/GLBenchmarking.cxx
+++ b/Utilities/Benchmarks/GLBenchmarking.cxx
@@ -71,7 +71,7 @@ class SurfaceTest : public BenchmarkTest
   {
   }
 
-  virtual vtkIdType Build(vtkRenderer *renderer, const vtkVector2i &res)
+  vtkIdType Build(vtkRenderer *renderer, const vtkVector2i &res) override
   {
     //vtkVector2i res(20, 50);
     vtkNew<vtkParametricBoy> parametricShape;
diff --git a/Utilities/Benchmarks/vtkRenderTimingTests.h b/Utilities/Benchmarks/vtkRenderTimingTests.h
index b2159525f3e..cdec8c18333 100644
--- a/Utilities/Benchmarks/vtkRenderTimingTests.h
+++ b/Utilities/Benchmarks/vtkRenderTimingTests.h
@@ -55,12 +55,12 @@ class surfaceTest : public vtkRTTest
     this->WithNormals = withNormals;
   }
 
-  const char *GetSummaryResultName() { return "Mtris/sec"; }
+  const char *GetSummaryResultName() override { return "Mtris/sec"; }
 
-  const char *GetSecondSummaryResultName() { return "Mtris"; }
+  const char *GetSecondSummaryResultName() override { return "Mtris"; }
 
-  virtual vtkRTTestResult Run(vtkRTTestSequence *ats,
-      int /*argc*/, char * /* argv */[])
+  vtkRTTestResult Run(vtkRTTestSequence *ats,
+      int /*argc*/, char * /* argv */[]) override
     {
     int ures, vres;
     ats->GetSequenceNumbers(ures,vres);
@@ -159,12 +159,12 @@ class glyphTest : public vtkRTTest
   {
   }
 
-  const char *GetSummaryResultName() { return "Mtris/sec"; }
+  const char *GetSummaryResultName() override { return "Mtris/sec"; }
 
-  const char *GetSecondSummaryResultName() { return "triangles"; }
+  const char *GetSecondSummaryResultName() override { return "triangles"; }
 
-  virtual vtkRTTestResult Run(vtkRTTestSequence *ats,
-      int /*argc*/, char * /* argv */[])
+  vtkRTTestResult Run(vtkRTTestSequence *ats,
+      int /*argc*/, char * /* argv */[]) override
     {
     int res1, res2, res3, res4;
     ats->GetSequenceNumbers(res1, res2, res3, res4);
@@ -267,14 +267,14 @@ class moleculeTest : public vtkRTTest
     this->AtomsOnly = atomsOnly;
   }
 
-  const char *GetSummaryResultName() {
+  const char *GetSummaryResultName() override {
     return this->AtomsOnly ? "Atoms/sec" : "Atoms+Bonds/sec"; }
 
-  const char *GetSecondSummaryResultName() {
+  const char *GetSecondSummaryResultName() override {
     return this->AtomsOnly ? "Atoms" : "Atoms+Bonds"; }
 
-  virtual vtkRTTestResult Run(vtkRTTestSequence *ats,
-      int /*argc*/, char * /* argv */[])
+  vtkRTTestResult Run(vtkRTTestSequence *ats,
+      int /*argc*/, char * /* argv */[]) override
     {
     int res1;
     ats->GetSequenceNumbers(res1);
@@ -406,18 +406,18 @@ class volumeTest : public vtkRTTest
     this->WithShading = withShading;
     }
 
-  const char *GetSummaryResultName()
+  const char *GetSummaryResultName() override
     {
     return "Mvoxels/sec" ;
     }
 
-  const char *GetSecondSummaryResultName()
+  const char *GetSecondSummaryResultName() override
     {
     return "Mvoxels";
     }
 
-  virtual vtkRTTestResult Run(vtkRTTestSequence *ats,
-      int /*argc*/, char * /* argv */[])
+  vtkRTTestResult Run(vtkRTTestSequence *ats,
+      int /*argc*/, char * /* argv */[]) override
     {
     int res1, res2, res3;
     ats->GetSequenceNumbers(res1,res2,res3);
@@ -529,12 +529,12 @@ class depthPeelingTest : public vtkRTTest
   {
   }
 
-  const char *GetSummaryResultName() { return "subsequent frame time"; }
+  const char *GetSummaryResultName() override { return "subsequent frame time"; }
 
-  const char *GetSecondSummaryResultName() { return "first frame time"; }
+  const char *GetSecondSummaryResultName() override { return "first frame time"; }
 
-  virtual vtkRTTestResult Run(vtkRTTestSequence *ats,
-      int /*argc*/, char * /* argv */[])
+  vtkRTTestResult Run(vtkRTTestSequence *ats,
+      int /*argc*/, char * /* argv */[]) override
     {
     int ures, vres;
     ats->GetSequenceNumbers(ures,vres);
@@ -655,12 +655,12 @@ class manyActorTest : public vtkRTTest
   {
   }
 
-  const char *GetSummaryResultName() { return "actors"; }
+  const char *GetSummaryResultName() override { return "actors"; }
 
-  const char *GetSecondSummaryResultName() { return "frames/sec"; }
+  const char *GetSecondSummaryResultName() override { return "frames/sec"; }
 
-  virtual vtkRTTestResult Run(vtkRTTestSequence *ats,
-      int /*argc*/, char * /* argv */[])
+  vtkRTTestResult Run(vtkRTTestSequence *ats,
+      int /*argc*/, char * /* argv */[]) override
     {
     int ures, vres;
     ats->GetSequenceNumbers(ures,vres);