21 famous Church of Scientology members

On Friday, HBO's explosive new documentary on Scientology, "Going Clear," opened theatrically in limited release. The film will premiere on HBO on March 29.

The Alex Gibney-directed documentary is based on author Lawrence Wright's controversial book "Going Clear: Scientology, Hollywood, & the Prison of Belief," which grew out of a New Yorker profile on former Scientologist, director Paul Haggis.

In the doc, Gibney takes aim at Scientology's most high profile members, like Tom Cruise and John Travolta, and addresses why the actors would have such a hard time leaving the religion.

But Cruise and Travolta aren't the only celebrity Scientologists.

From "Mad Men" stars to "Orange Is The New Black" actors, see who else is part of the controversial religion.

With additional reporting by Ashley Lutz.