"It's incredibly powerful particularly when celebrities come forward and share their stories on survival," Katherine Hull, vice president for communications at RAINN, told ABCNews.com. "It tells other people they are not alone. And seeing someone who has experienced this crime, and has survived it and is thriving today shows survivors and victims that recovery is possible."
Fisher, who wrote about his claim of being sexually abused at the age of six by a woman taking care of him in his memoir, "Finding Fish," has seen firsthand the impact his book and the film based on it, "Antwone Fisher," has had on people.
Through his Web site and Twitter, he has heard from people as far away as China.
"The very thing I was most ashamed of turned out to be the thing that helped other people," he said.
Fisher is especially proud to be giving a face to abuse perpetrated by women.
"We have to protect boys the same way we protect girls," he said.
Byrne, star of HBO's "In Treatment," said he experienced sexual abuse two different times. The first time was when he was an altar boy at a Christian Brothers School in Ireland.
"It was a known and admitted fact of life amongst us that there was this particular man, and you didn't want to be left in the dressing room with him," Byrne told the Irish television show. "There were certain boundaries, sexual boundaries, [that] were crossed. And it was mixed up with fear and ultimately with shame.
"I had the misfortune, when I went to England to seminary, there was another incidence of it, and I had to face it again. I was unlucky in that way," he added. "It didn't go on for a very prolonged period, but it happened at a very, very vulnerable moment."
Byrne said he didn't feel the impact immediately.
"But I suppose when I think about my later life and how I had difficulties with certain issues, there is the real possibility they could have been attributable to that," said the actor, who has battled alcoholism.
Fisher said talking about sexual abuse serves another purpose for celebrities: It's healing.
"I feel like because I was the kind of person who never let go, I had a head start on healing," he said. "The abuse never goes away because it's a part of your life."
"I feel sorry for other people who haven't found a way to make sense of it," he added. "The shame keeps some people from getting better."
That's what "Desperate Housewives" star Teri Hatcher discovered when she finally went public in 2006 with a claim of sexual abuse at the hands of an uncle when she was five.
"This is something I've tried to hide my whole life," she told Vanity Fair.
But the actress was compelled to act in 2002 after she learned that a 14-year-old victim of her uncle had committed suicide.
After Hatcher told prosecutors her story, her uncle, Richard Hayes Stone, then 64, pleaded guilty to four counts of child molestation in the case of the 14-year-old victim and received 14 years in prison.
Chuck Gillingham, the Santa Clara County deputy district attorney in California, told The Associated Press in 2006: "Without Teri, this case would have been dismissed."
Getting help: Contact National Sexual Assault Hotline at 1-800-656-HOPE or online at rainn.org