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.
MyPaint - MyPaint is a fast, distraction-free, and easy painting tool for digital artists.
Corel Painter - Corel Painter is media painting software.
Fresh Paint - Microsoft's new painting software with more realistic brushes for Windows 10
Pixlr - Pixlr® makes it easy to transform everyday images into stunning works of art.
GIMP - GIMP is a multiplatform photo manipulation tool.