Blender - Blender is the open source, cross platform suite of tools for 3D creation.
MakeHuman - MakeHuman is a free, open source, interactive modeling tool for creating custom 3D human characters.
Quixel Mixer - Mixer is a PBR creation suite that uses brushes and non-destructive layering to generate all types of maps.
Bforartists - Bforartists is a fork of Blender.
3D-Coat - 3D-Coat is the one application that has all the tools you need to take your 3D idea from a block of digital clay all the way to a production ready, fully textured organic or hard surface model.
Art of Illusion - Art of Illusion is a free, open source 3D modelling and rendering studio.