Other A-listers who have decided to leave behind the talked-about religion include Cruise's ex-wife Nicole Kidman, comedian Jerry Seinfeld, actor Jason Beghe and film director Paul Haggis.
Kidman, 45, left Scientology after her divorce from Cruise in August 2001. Karen De La Carriere, ex-wife of former Scientology president Heber Jentzsch, claimed to The Hollywood Reporter that members of the church deliberately turned Kidman and Cruise's children, Bella, 19, and Connor, 17, against their mom after their parents split.
"You're either in or out when it comes to Scientology," another expert told THR. "That's why Katie is making custody such an issue in the divorce petition. If you're out, the way she seems to be, they want to cut you off from everyone, including your kids."
G.I. Jane actor Jason Beghe famously left the church in 2007 -- after 13 years. He released a video rant in 2008 speaking out against the group. "Scientology is destructive and a rip-off," the 52-year-old actor said. "It's very, very dangerous for your spiritual, psychological, mental, emotional health and evolution. I think it stunts your evolution. If Scientology is real, then something's f---ed up."
Jerry Seinfeld admitted in 2007 that he studied Scientology for a brief time. "I did some Scientology courses about 30 years ago," Seinfeld, 58, told Access Hollywood. "The only thing that bothers me about people knowing that is that it is not my complete wacko resume. It's just one aspect!"
"I didn't do very much. I don't know that much. I just did a little but I liked it," he said.
Why did he stop? "I don't know . . . I was kind of flitting from thing to thing. I was interested in exploring."
Film director and screenwriter Paul Haggis left Scientology in October 2009 after being an active member for 34 years. He wrote a resignation letter to the church after the San Diego branch made statements supporting Proposition 8.
"I was in a cult for thirty-four years," Haggis, 59, said via a story written in The New Yorker in February 2011 detailing his allegations. "Everyone else could see it. I don't know why I couldn't."
Actress Diana Canova, best known for her role on the 1970s sitcom Soap, told Premire magazine in 1993 she had a hard time leaving the religion. "It took me years before I decided to quit," Canova, 59, said. "I guess finally I was so fed up with being afraid. You've heard all these horror stories . . . I believed them."
As for Holmes, she was raised as a Catholic but converted to Scientology after getting together with Cruise, 50, in 2005. Sources tell Us Weekly the 33-year-old actress and Cruise "fought viciously" over how to raise their six-year-old daughter, Suri. At one point, Holmes had been attending Scientology classes three times a week, but stopped going a year and a half ago.
Wikipedia's list of famous Scientologists can be read here.
What I find both sad and scary about this is that after commenting on all this Scientology disconnection, Karen De La Carriere's son mysteriously died.