Kobe Bryant, Ricky Martin, Neil Patrick Harris and Steve Nash were among the celebrities and athletes tweeting support for Jason Collins' coming out on Monday.

Collins, a 34-year-old 12-year NBA veteran and currently a free agent, came out gay in a cover story for Sports Illustrated, making him the U.S.'s first openly gay professional athlete.

(Related: NBA's Jason Collins: First openly gay professional athlete.)

“Bravo, @JasonCollins34! Thanks for stepping up,” actor Neil Patrick Harris messaged. “For standing tall. And at 7 feet, that's saying a lot.”

Minnesota Viking punter Chris Kluwe tweeted: “Big kudos to @JasonCollins34. Living proof that your sexuality has nothing to do with your athletic ability.”

Former Baltimore Ravens linebacker Brendon Ayanbadejo added: “By @JasonCollins34 opening doors & doing it his way on his time he has helped shape a more accepting America. Many many more follow #courage.”

Several NBA stars, including Kobe Bryant, Steve Nash and Martell Webster, also applauded Collins.

“Proud of @JasonCollins34. Don't suffocate who u r because of the ignorance of others #courage #support,” messaged Bryant.

Nash wrote: “The time has come. Maximum respect.”

“@JasonCollins34 you have made sports what it should be and that's 'OPEN' proud of you for being you. That jump shot is still weak lol,” added Webster.

Singers Ricky Martin and Lance Bass also congratulated Collins.

“I don't know you personally @JasonCollins but … CONGRATULATIONS buddy! You are a brave man! I'm very happy for you!”

“Congrats @JasonCollins34!!” Bass messaged. “Giant leap for sports – and the conversation continues!”