She-Hulk Rig is a free Maya rig made by @CromaCore_. Download it from his Gumroad page!
She-Hulk Rig
Kratos Rig
Kratos Rig is a free Maya rig made by @CromaCore_. Download it from his Gumroad page!
ProRigs
ProRigs are Maya rigs developed by talented artists from animation studios such as Disney, Dreamworks, Pixar and Sony. Available on a subscription model which gets you access to over 40 rigs.
Grease Pencil
Grease Pencil is a feature inside Blender that allows you to animate in 2D while taking advantage of a full 3D suite of features. Definitely one of the best pieces of software that blends the two together so seamlessly (and free!)
I Want to be an Animator
I Want to be an Animator is a Youtube collection of free Lessons, Tutorials and Tips about 3D Animation, mostly focusing on the basics and principles.
Akeytsu
Akeytsu is a piece of 3D animation software and is a lighter, faster and cheaper alternative to Maya. It also has a free educational version.
MakeHuman (FREE)
MakeHuman is a free open-source software that allows you to create and pose 3D human characters. Useful for pose reference.
Mery Rig (FREE)
The Mery Rig is a Free Rig project by José Manuel García Alvarez and Antonio Méndez Lora and works with Maya 2013+
Highend 3D Rigs (FREE)
Highend 3D is a website that has a bunch of free rigs available to download and ranges from Homer Simpson to Spiderman and more!
Animator's Resource Kit 