Planet of Oirgin: Xetox
Known representative: The Great Gazoo
Xetoxians are inhabitants the planet Xetox. They were already a highly advanced technological interstellar civilisation when mankind appeared on Earth. They are very intelligent small green humanoids with heads as big as the rest of their bodies.
One of them, known as the Great Gazoo, was exiled to Earth as punishment for having invented a weapon of infinite destructive power. There, to redeem himself, he used his advanced scientific powers to perform good deeds for two prehistoric men, Fred Flinstone and Barney Rubble.
Source: animated cartoon series THE FLINTSTONES/ABC/1960-66 (voiced by Harvey Korman) and , The Flintstones in Viva Rock Vegas (Alan Cumming) (2000)