Blender

Blender is a free open source 3D graphics program, available under the GNU General Public License for the Linux, Mac OS X, FreeBSD, OpenBSD and Microsoft Windows operating systems.

Blender's features include 3D modeling, UV unwrapping, texturing, rigging, water and smoke simulations, skinning, animating, rendering, particle other simulations, video editing software, compositing, the ability to create interactive 3D applications, video games, animated film, or visual effects. More advanced tools include rigid, realistic body, fluid, cloth and softbody dynamics simulation, modifier-based modeling, character animation, a node-based material and compositing system, and embedded scripting in Python.