Hulk (Firelight) - (free) Maya Animation Rig

 Hulk is a free Maya animation rig availabe at Firelight.

Blue (Lupin House) - (free) Maya Animation Rig

 Blue is a free Maya rig available at Lupin House.

Monkey (ProRigs) - (paid) Maya Animation Rig

 Monkey is a paid Maya animation rig available at ProRigs.

Vixen - (paid Maya Animation Rig)

 Vixen is a paid Maya animation rig available here.

Knight Spider (free Maya Rig)

Knight Spider is a free Maya animation rig by The Rookies available here, which is part of a contest you can read about here.

Harlow (paid Maya Rig)

 Harlow is a paid Maya animation rig by "Built by Colossus" and available here.

Stewart (paid Maya Rig)

Stewart is a paid Maya animation rig and available here.

Tom (Free Maya Rig)

 Tom is a free Maya animation rig and available here.

Skaarj

More info here.

Reptilian

More info here.

Megalodon

More info here.

Midi

More info here.

Rhino

More info here.

Kit

More info here.

Kaju

More info here.

Tanner Saurus Rex

More info here.

Cartoon Eyes

More info here.

Venus Flytrap

More info here.

Squid

More info here.

Spongebob

More info here.