MyPaint - MyPaint is a fast, distraction-free, and easy painting tool for digital artists.
ibis Paint X - Drawn with + ibisPaint
GIMP - GIMP is a multiplatform photo manipulation tool.
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.
Corel Painter - Corel Painter is media painting software.
Huion Sketch - Huion Sketch is an animation and drawing application that comes with all the tools and features, providing you ease when making a painting.