Aseprite - Aseprite is an art program dedicated to the creation of pixel art.
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.
Piskel - Piskel is a website where designers online create sprites or pixel art.
GIMP - GIMP is a multiplatform photo manipulation tool.
Cosmigo Pro Motion - Pro Motion is a drawing and animation software for Windows designed similar to the famous Amiga...
Paint.NET - Paint.NET is a free image and photo editing software.