Bforartists - Bforartists is a fork of Blender.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
Art of Illusion - Art of Illusion is a free, open source 3D modelling and rendering studio.
MakeHuman - MakeHuman is a free, open source, interactive modeling tool for creating custom 3D human characters.
MagicaCSG - MagicaVoxel Official Website
AC3D - AC3D is a 3D software for games, virtual reality and flight simulation, scientific, medical and general data visualisation, rapid prototypes of 3D designs, 3D printing, Google Earth, X-Plane, Second Life and more.