Credit: Jordan Strauss/

Anna Paquin has come out of the closet.

The True Blood star says "I'm bisexual, and I give a damn," in a new online public service announcement for the Give a Damn Campaign, aimed at promoting gay, lesbian, bisexual and transgender equality.

Now 27, Paquin dated actor Kieran Culkin in 2007, and has never discussed her sexuality with the press. She became engaged to True Blood costar Stephen Moyer, 40, in August 2009. The couple hasn't yet announced their wedding date.

"We always take the p--- out of each other and are silly with each other, and it is great," Brit actor Moyer has said. "We're very, very happy. She's the best."

Launched Thursday, the "Give a Damn" campaign -- featuring Elton John, Whoopi Goldberg, Sharon and Kelly Osbourne, Wanda Sykes and others -- is part of singer Cyndi Lauper's True Colors Fund.

"In my life I've crossed paths with many different people and I've seen firsthand what it means to be discriminated against," Lauper says. "As a straight person, I have a responsibility to stand up for gay and transgender people each and every day. We all have to get involved; we all have to give a damn."