Zira a veternarian and medical researcher travels in time and reaches present day America. At first she is thought to be nothing more than an animal who has learned the art of mimicry. But before a grand commision she shows herself to be more than just a dumb animal. The audience in the room applaudes her speach even. Zira speaks at womens causes and appears to have assimilated well with humans. But the stories of Ape's dominating the world in the future cause many to be uneasy. Zira who is pregant is ordered to have an abortion. She escapes with Cornelius and is later shot dead..

Cornelius played by Roddy McDowall

Cornelius an archaelogist, and a proponent of evolution on his world arrives in present day America. But is very suspcious of everything. He befriends a doctor that helps him to escape with his wife, but ultimately he is killed but not before giving birth to a succesor that will lead the Apes in revolt in the next film..

Dr Lewis Dickson played by Bradford Dillman

Dr Dickson is a pschologist and expert in veternary science. He first notices the incredible intelligence of Cornelius an Zira and comes to think of them fondly. He finds the govermen't plans to abort Zira's baby to be unfair and ultimately helps Zira and Cornelius to escape.

Dr Milo played by Sal Mineo

Dr Milo is the third of a trio of Chimpanzees that arrives from Earth's future to present day America. Milo repaired the spacecraft that lead them to Earth and understands thing better than either Zira or Cornelius do in this respect. Milo believes the three chimpanzees should remain quiet until they know their friends from their enemies. Zira however gets mad and speaks ending this plan. Milo is killed in a zoo by a large gorilla in a neighboring cage which chokes him to death.

Dr Otto Hasslein played by Eric Braeden

A senior Scientific advisor to the President of the United States. Hasslein beliees the only way to prevent Ape dominance of man in the future is to kill Zira, Cornellius and their baby. The President however thinks aborting their baby is all that is necessary. When Zira and Cornellius escape Hasslein uses their escape to justify hunting them down which he does.