These 3d models are contributed by John Hoffman and are based on characters from a cartoon show called "Jayce and the wheel warriors" (except the marauder)
John's site: SplittingPixels

Free the models is a site that offers free 3d models in 3ds, wavefront, bryce, poser, lightwave, md2 and unity3d format. Also a great collection of textures to use in your favorite modelling and rendering program.
All the content is free for any use.