open source
Blender was first conceived in December 1993 and became a usable product in August 1994 as an integrated application that enables the creation of a diverse range of 2D and 3D content. Blender provides a broad spectrum of modeling, texturing, lighting, animation and video post-processing functionality in one package. Through its open architecture, Blender provides cross-platform interoperability, extensibility, an incredibly small footprint, and a tightly integrated workflow. Blender is one of the most popular Open Source 3D graphics applications in the world.
http://www.blender.org/download/get-blender/