Louise is a free high res facial rig for Maya, Unreal and Unity with a complete set of 236 blendshapes
Louise – Facial Rig
Animate With Arran
Animate With Arran is a YouTube channel by Arran Baker who has recently started to post some great free videos around animation process, workflow tips and more.
Ystra – Astral Witch
Ystra – Astral Witch is a free Maya rig by Christoph Schoch based on the concept by Alexis Pflaum. Download it HERE
Henry Rig (Free)
Henry rig is a free rig made by students from Cogswell University
Built By Colossus Rigs
Built By Colossus Rigs are free and paid Maya rigs available for download. Founded and run by Roman Jeffery.
BOTW Link Rig
BOTW Link Rig is a free Maya rig based on the Breath Of The Wild version of Link (similar to the previously posted Zelda Rig). Made by Christoph Schoch.
Agora Studio Rigs
Agora Studio have been creating a bunch of Maya rigs and releasing them for free primarily to be used in the AnimChallenge. Check them out HERE
Zelda Rig
The Zelda Rig is a free Maya rig made by Christoph Schoch and is available on his Gumroad page
Link Rig
The Link Rig is a free Maya rig made by Christoph Schoch and is available on his Gumroad page
Animator's Resource Kit 