Blender. Open source 3D graphics editor
Blender is a 3D modeler, animator, renderer, post-processor, video editor, game engine… you name it. It’s a free and open source alternative to software like 3DS Max or Cinema 4D. Its interface is not the easiest to learn, and the amount of features included can be overwhelming, but patience will be rewarded. It’s in active development, is rapidly evolving, and it gets better and better with every version. You can get Windows, Mac and Linux versions.
It has been used to create a number of short films. The last one is the first part of Cosmos Laundromat:
There are lots of online resources to learn Blender, most of them in English. Jacob Lewis has an Absolute Beginners Tutorial series on YouTube: