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.
Epic Pen - A windows tool for drawing over your desktop and applications
Artrage - A simple but lovely natural media painting and sketching program.
MyPaint - MyPaint is a fast, distraction-free, and easy painting tool for digital artists.
PaintTool SAI - Learn to draw in different ways.
Clip Studio Paint - The artist's software for drawing and painting.