Gleek is a blue "space monkey" and the pet of Zan and Jayna, the Wonder Twins. Gleek is often used as comic relief for the series, as the character often gets into mischief. A joke involving Gleek often ends episodes of the Super Friends in which he appears. Gleek has a stretchable, prehensile tail which can be quite useful, it is shown to be capable of picking up a man. Gleek is also highly intelligent, as he clearly understands spoken English. He communicates through the use of sign language, acting out scenes, and chattering in an unintelligible alien tongue. Gleek also helps the Twins when they need to travel: Jayna becomes an eagle, Zan becomes water, and Gleek produces a bucket to hold Zan while Jayna carries them both. In one episode other monkeys of Gleek's species appear and try to take over the world. Their Leader is able to speak English apparently. They are able to brainwash Gleek and he helps them find the weaknesses of Superman, Wonder Woman, Batman and Robin.
Executive producer Brian Peterson confirmed that Gleek would appear "in one shape or another" in Smallville's eighth episode of season nine, "Idol." In fact, Gleek appeared as a decoration on Jayna's cellphone and Gleek's chuckling guffaw was the ringtone.
Gleek appears in the Robot Chicken episode "Major League of Extraordinary Gentlemen" in the sketch "Sidekick Elevator". This sketch he is shown alongside Orko from the He-Man series and Snarf from Thundercats. He then gets into an unemployment line only to be greeted by Andy Richter.
Gleek appears alongside Zan and Jayna in Adult Swim's "The New Adventures of the Wonder Twins," a series of five Webisodes released in 2007.