Dibuja - Gtk based basic paint program like MSPaint or Paintbrush but for Linux
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.
Affinity Photo - Affinity is the imaging and design suite for creative professionals exclusively for Mac.
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.
MS Paint IDE - The most partially downloaded IDE on the internet