Challenger Jacobus is a Youtube playlist made by Eric Jacobus where he performs movesets from beat-em-up games in real life. Great resource for animation reference!
GreenScreen Animals is an extensive library of domestic and exotic animals video footage in high definition.
SloMo Ref is a free collection of slow motion animal reference videos on Youtube
Endless Reference is a Youtube channel that focuses on animation reference. Lots of great human locomotion videos from different angles
Bodies in Motion is an ongoing photographic project that aims to document the power, beauty and possibility of the human body in motion. It is freely accessible to all visitors at preview resolution or you can subscribe for higher quality images.
MakeHuman is a free open-source software that allows you to create and pose 3D human characters. Useful for pose reference.
Keyframe MP is is a compact, yet powerful, media player designed to meet the needs of animators. Features include scrubbing (with audio), single frame stepping, an adjustable playback range and bookmarks. Free Trial available.
Iamag.co is a huge collection of references for walk cycles. The collection contains illustrations, sketches, model sheets and tutorials…
Posemaniacs is good free resource for searching for specific poses at various angles. It has 1000s of poses displayed by male and female 3D models.