“I intend to make Scientology as accessible to as many people as I can. And that is my goal,” Elfman said. To do this, she says, it is my “duty to clear the planet.” By “clearing” she means to rid the world of “body thetans” — aliens who Scientologists believe inhabit the earth from a nuclear explosion 75 million years ago. She continued that “the more successful I became, the more suppression I bumped into … especially in the entertainment industry, which really is home to rabid suppression.”

Though Scientology has some pretty strange views regarding space aliens- what Hubbard generally describes as Space Opera, the above is inaccurate. There is no term is Scientology called “body thetans”. The word "thetan" is a Scientology term. And in Scientology, everyone is a thetan; it means the person which is distingished from the mind and the human body- spirit or soul has similar meaning.
And the word "suppression" is very specific term in Scientology.
Briefly, it's concerning a fairly rare personality type. And she is sort of misusing using this term also. For instance in Scientology, aliens wouldn't normally be a cause of "suppression"- that would a sign of insanity in the Scientology world as it is elsewhere:)

Btw, the philosophy of Scientology would divide existance into the MEST [Matter, Energy, Space, and Time] Universe and the Theta Universe. So in a sense, according to Scientology, everyone is an "alien" in this physical universe.
Btw Btw, Hubbard considered that most science fiction which has ever been written is based on actual events in the distant past. So for example the opening sentences in "Star Wars" makes sense and is more "accurate" as far as Scientology is concerned.