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 has been 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 alien language (unintelligible to the audience). 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.
- He reuses the Zookeeper's chimpanzee.