Skiff Xounellius is the teenage alien in Planet 51. His friends are Lem, Neera and Eckle. He is Lem's best friend and likes Rover.
Like Eckle, he likes Humaniacs and his employeement was formerly at the Comic Book Shop as an assistant.
Skiff was recycled from the American Dad character "Roger" but he's green, with antennas, stretched out legs and thin arms and legs, skinny, realistic pupils on eyes and younger age.
- Skiff is the only character that came from another TV show for Planet 51.
- Skiff continued to appear on every episodes of American Dad as Roger.