Comedienne and talk show host Ellen DeGeneres made an appeal on The Tonight Show, showing her support for gay marriage.
In November, Californian citizens will vote on Proposition 8 of the state constitution, which would define marriage as existing between one man and one woman only.
If the proposition is rejected, gay marriage will remain legal in California.
Following her wedding to actress Portia de Rossi earlier this year, Ms DeGeneres made a plea to other Californian’s to vote no to the proposition.
She said: “I got to do something this year I never thought I’d ever be able to do: I got married. It was the happiest day of my life.”
“There are people out there raising millions of dollars to try and take that right away from me.
“You’ve seen their ads on TV. They’re twisting the truth, and they’re trying to scare you.
“I believe in fairness. I believe in compassion. I believe in equality for all people. Proposition 8 does not.
“Please, please, vote NO on Prop. 8.”
Several celebrities have donated money to the campaign to reject Proposition 8.
Mayor of LA Antonio Villaraigoso, Steven Spielberg, Brad Pitt, Pete Wentz and TR Knight have all made contributions