Well that's a surprise. Pixar Renderman, the software used and developed by Pixar to turn computer-represented geometry into wonderful images, is now free for non-commercial use. This is not quite as free as Unreal Engine 4, which does not require royalties for rendered audio/video at all because the content is viewed without the engine, but free for non-commercial is still a big deal considering what Renderman is. While Pixar is known for their movies, they are very much software engineers.
Thumbs up all around.
Image Credit: Pixar via Animation Magazine
Currently the rendering package integrates with Autodesk Maya and KATANA by The Foundry. Pixar has Cinema4D and Houdini listed as “in development”. They also claim to be interested in 3D Studio Max, because of course they are, as well as Modo, Rhino, Lightwave, and Blender.
The above list only considers dedicated plug-ins. Pixar Renderman can also be run as a standalone application that accepts their file format, “RIB”, from a command-line interface. There has been many of these for Blender and other 3D suites over the last basically forever. A plug-in is nicer for artists however, and it is good to see Pixar is not afraid of open-source suites to pair with their proprietary rendering package. Also, "Blenderman" is a hilarious name.