Bradley Biggle, also known by his real name Gok'zarah, or by his superhero name Mint-Berry Crunch, is an alien from the planet K'oh Kajan, who discovers his origins in the Season Fourteen episode "Coon 2: Hindsight". He wears a human disguse and his powers and abilities include fighting, super-human strength, teleporting in a splash of berries, and immortality.
Kevern Zaksor is the Ambassador to New Planet Testing. He initially appeared as a notorious gangster who is under pursuit by the Intergalactic Police for stealing "space cash", all being just a part of a test. He appeared in the Season Thirteen episode "Pinewood Derby".
Marklar are an intelligent species of aliens who refer to everything as "Marklar". Even if they're almost identical and they are all having the same name, they are still somehow able to tell each other apart. They appeared in the Season Three episode, "Starvin' Marvin in Space".