Letta
Letta is a recurring alien villain in My Life as a Teenage Robot. She is the leader of the Space Bikers and the principal of their home planet's elementary school. She holds a personal grudge against Jenny for destroying her bike. She is voiced by Grey DeLisle.
History
Letta and her gang are from a planet that is inhabited by peaceful fish-like aliens. Her identity as a Space Biker had been a secret (until Jenny and Tuck expose Letta and her cohorts as dangerous villains in Voyage to the Planet of the Bikers).
Letta was the principal of an elementary school on her home planet. But she and her gang sneak away and don their biker personas to blow off steam on the weekends and wreak havoc for fun, usually by crashing parties on other planets, such as Earth.
Because she holds a grudge against Jenny, Letta often returns to Earth with the Space Bikers to torment her and her friends.
She attends the wedding of Tammy in Ball and Chain