Fan Casting Zookeeper in Return to the DC Universe

A scientist who worked besides Mark and Marie Logan years ago, Dr. Samuel Register was there when Garfield Logan was infected by Sakutia and his survival. Believing the Logans had found the missing link between humans and animals, Register continued his research, eventually pulled to work for S.T.A.R. Labs, until he stole a sample of Sakutia from the CDC and infected himself and others. Like Beast Boy, Register has gained the ability to transform into all animals, and has come to hate Gar for his condition, working in many ways to crush him.