Konga

Konga is a mutant chimpanzee and the titular secondary antagonist in the 1961 British film of the same name.

History
Konga was a baby chimpanzee found in Africa by British botanist Charles Decker. He was brought to London where Dr. Decker made him the subject of his hideous experiments. The insane botanist creates a serum that turns Konga into a ferocious gorilla-sized ape, then he mesmerizes the chimp and sends him kill all his former enemies.

Konga killed many people, one of his victim was Bob Kenton, one of Decker's students and the lover of Sandra Banks, another students that  Decker wants for himself. Decker attempts to seduce Sandra after Bob's death, but Margaret, his assistant and current girlfriend, became jealous and tried to get revenge by giving a large amount of serum to Konga then ordered him to attack Decker and Sandra.

However, the serum transforms the ape into a giant monster. He killed Margaret before he caught Dr. Decker then he ravaged the city. He finally killed Decker but he was attacked and killed by the British army. Upon his death, he reverts to a chimpanzee.

Trivia

 * Konga is a homage to King Kong.
 * Konga was assumed to be the main antagonist, but the true villain is Decker.