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.
Artrage - A simple but lovely natural media painting and sketching program.
Corel Painter - Corel Painter is media painting software.
Procreate - Procreate is the most powerful and intuitive digital illustration App available for iPad®.
Clip Studio Paint - The artist's software for drawing and painting.