"I'm bisexual," Paquin added that "hated is a crime committed every hour of every day in this country."
Paquin has been accepted for years, engaged to her boyfriend Stephen Moyer.
Lauper, Whoopi Goldberg, Elton John and Sharon Osbourne are among the other stars that appear in the message.
"I have the equality of means for those who are not realized, and, as an honest man, I have a responsibility to defend the days of homosexuals and transsexuals in the world," Lauper said in a statement.
Statement by Mr. Paquin was a surprise to fans of his work in film and television, with the Oscar for best actress in 11 years in 1993.
Since 2008, Canada was a person born in the television series Paquin Vampire telepath played "True Blood" on the cable network HBO.
