Both Zan and his twin sister Jayna are form the planet Exxor and they have a monkey named Gleek.
Their first appearance was in the Superfriends TV show. They also appeared in the Superfriends comic (where they were much more competent than portrayed on the television version).
For their powers to activate they have to touch knuckles and they have to say "Wonder Twin Powers Activate". Zan can transform into any state of water: liquid, ice, steam, mist; or an ice structure: for example an ice cage or an ice sled. Jayna can transform into any animal, even extinct, mythical, or alien.
An updated version appeared as an alien slaves in Extreme Justice (a JLA spin-off) and after Zan and Jayna fought with the team they later became members of that version of the Justice League. Later they appeared as members of Young Justice wearing new costumes that closely resembled normal clothes for a teenager (with their initials on them) instead of their purple and black slave suits with gold power harnesses.
When Zan makes physical contact with his sister he can turn into water in any state (ice or vapor as well as water) and can even become a ice monster or a living water creature. He can partially shift his body to turn his fingers into ice claws. He shares a telepathic link with Jayna
In other media
Smallville (TV Series)
The past of Zan and his twinsister Jayna is unknown. Both always told, they are transfer students from Sweden but know one believed that. Since that, Zan and Jayna lived on the streets their whole life. The only other history they have was that they once had a father who told them to always stay together, because they are stronger as a team. The origin of their powers is also unknown. Zan and Jayna are proud fans of The Blur (later known as Superman) and tried to follow in his footsteps.
Zan was portrayed by the actor David Gallagher. Both, Zan and Jayna only appeared in one episode of season nine, called "Idol".
After the end of the TV series, Smallville continued as a comic book. Zan and his sister first re-appeared in Smallville: Titans as members of the "Smallville" version of the Teen Titans. They both appeared a few times after their first re-appearance as minor characters.
Justice League Unlimited (Cartoon Series)
In the Justice League Unlimited cartoon a version appeared named Downpour.