What was the name of the alien character in The Flintstones?

The alien character in The Flintstones was The Great Gazoo.

Gazoo was a tiny, green, floating scientist from the future who appeared during the show’s final season. He was exiled to prehistoric Earth after inventing a doomsday device, then encountered Fred and Barney after his flying saucer crashed. His futuristic powers included teleportation, time manipulation, and materializing objects.

The character usually addressed Fred and Barney as “dum-dums” and attempted to help them with advanced technology. His interventions almost always created additional trouble, making him a comic disruption to the show’s otherwise Stone Age sitcom setting. Only certain characters, including Fred, Barney, and the children, could see him.

The Great Gazoo is sometimes confused with the fictional planet or species associated with him. He is a Zetoxian, but “Zetox” is not the character’s name. Harvey Korman provided Gazoo’s voice in the original series, beginning with his 1965 debut.