Exxor

Exxor is a planet in the Superfriends franchise.
It is the home planet of the Wonder Twins and Gleek. Although it is mentioned several times, beginning with The All-New Superfriends Hour, it is seen onscreen only once. In the episode, "The Demons of Exxor," the Wonder Twins and Gleek are summoned back to Exxor to deal with the alien villain Dar-Con, and the rest of the Superfriends have to rescue them.
* Also, in The World's Greatest Superfriends episode "Lex Luthor Strikes Back," the Wonder Twins and Gleek leave Earth to spend the weekend on Exxor, and do not take part in the action.