MyPaint - MyPaint is a fast, distraction-free, and easy painting tool for digital artists.
Krita - Krita is a professional FREE and open source painting program. It is made by artists that want to seaffordable art tools for everyone. Concept art. texture and matte painters, illustrations and comics.
Autodesk SketchBook - SketchBook drawing and painting software provides designers, architects, and concept artists the tools to sketch ideas quickly and create beautiful illustrations.
Corel Painter - Corel Painter is media painting software.
Clip Studio Paint - The artist's software for drawing and painting.
GIMP - GIMP is a multiplatform photo manipulation tool.