Takei (left) and Mr Altman celebrated with a Vulcan hand-sign
Actor George Takei and his partner were among the first Californian couples to get a wedding licence after the state lifted its ban on same-sex marriage.
Takei, 71, best known for playing Mr Sulu in Star Trek, received his licence in West Hollywood on Tuesday.
But the actor has said he does not plan to marry long-term partner Brad Altman until September.
"Congratulations to all of us and may equality live long and prosper," Takei told a cheering crowd.
He added: "I see before me people who personify love and commitment, people who are the personification of joy and celebration.
"Brad and I are going to get our marriage licence today - isn't that extraordinary? Isn't that wonderful?"
Last month California's Supreme Court said the "right to form a family relationship" applied to all Californians regardless of sexuality.
West Hollywood officials conducted a ribbon-cutting ceremony on Tuesday morning to mark the start of licences being issued for gay couples.
They also set up six flower-bedecked "marriage cabanas" to allow couples to exchange vows within minutes of collecting their wedding licences.
Takei, who recently appeared in the popular US TV series Heroes, and 54-year-old Mr Altman have been together for 21 years.
Last month he said they were going through the "delicious dilemma" of where to marry.
"We can have the dignity, as well as all the responsibilities, of marriage. We embrace it all heartily," Takei wrote on his website.