billie jean king
Billie Jean King has been one of the most outspoken advocates for gay rights. Reuters

The U.S. Supreme Court ruled in a 5-4 decision on Friday that states cannot prohibit same-sex couples from marrying. The decision came on the eve of New York City's Gay Pride Parade weekend, and has prompted a slew of messages on social media in support of gay rights.

In recent years, there have been more athletes who have become openly gay, as the five major North American sports have made inroads with the gay and lesbian community. Some gay athletes have waited until they retired to make statements like former NBA center John Amaechi and Major League Baseball outfielder Billy Bean, but NBA forward Jason Collins, NFL defensive lineman Michael Sam and MLS attacking midfielder Robbie Rogers made their announcements as they approached or during their professional careers.

On Sunday, gay athletes made statements on Twitter in support of the gay marriage ruling.