GIMP
(GIMP)
toolCross-platform raster retouching and compositing, scriptable in Python and Scheme via plugins
Digital Painting. Creative Freedom.
(Krita)
toolGPL painting program with brush engines, layers, assistants and animation; Linux, Windows, macOS
Blender - The Free and Open Source 3D Creation Software — blender.org
(Blender)
toolGPL 3D suite: modelling, sculpting, UV, Cycles path-tracing, VFX and Python-scriptable tooling
darktable
(darktable)
toolRaw developer and photo workflow manager; non-destructive edits over a database of negatives
Kdenlive - Free and Open Source Video Editor
(Kdenlive)
toolKDE's non-linear editor, also running on Windows, macOS and BSD; KDE-versioned quarterly releases