The Masters: President Trump leads the reaction to Rory McIlroy's dramatic Masters win
Legendary golfers and politician lined up to send their congratulations
Donald Trump paid tribute to Rory McIlroy's Masters title win - from on board Air Force One.
The US President congratulated the Holywood star on "showing tremendous courage".
"He showed great guts and stamina - people have no idea how hard that is," he added.
McIlroy won his first-ever Masters after beating Justin Rose in a play-off hole following a dramatic final day at Agusta.
In doing so, he became only the sixth golfer in history to win a career Grand Slam.
The sport's most exclusive club also includes Tiger Woods, Jack Nicklaus, Gary Player, Ben Hogan and Gene Sarazen who have all won all four major titles.
Woods posted on social media, ""Welcome to the club @McIlroyRory.
"Completing the grand slam at Augusta is something special. Your determination during this round, and this entire journey has shown through, and now you're a part of history. Proud of you!"
McIlroy's close friend Shane Lowry joked that McIlroy could happily retire after completing the career grand slam.
"This means everything to him," Lowry told Golf Channel.
"This is all he thinks about, all he talks about. He always said to me he'd retire a happy man if he won the green jacket, so I told Erica (McIlroy's wife) he can retire now.
"He's had a long 10, 11 years, he's had a lot of hurdles to get over and it's a credit to him."
Tommy Fleetwood, who finished 21st after a closing 69, added: "I've said it a bunch of times, I think Rory is the best player of our generation. I don't think he's had to prove that for a while.
"For him to have finally got this one, a career grand slam, is unbelievably special. I think this time was always going to come, it's just Rory makes you feel like it's not going to at some point.
"Whatever he did today, Rory's place in golf (history) was secure, but this has just added another layer on top of that.
"I do believe he's the best of our generation and now he's one of the greatest of all time."
The President of Ireland Michael D Higgins joined political leaders from across the island in celebrating McIlroy's victory, calling it a "truly outstanding achievement".
Northern Ireland's First Minister Michelle O'Neill said the Holywood golfer's "incredible" triumph placed him among the sport's greatest.
"This is a huge moment in sporting history, and one that has filled everyone back home with great pride and that will undoubtedly inspire future generations to chase their dreams," she posted on X.
"Enjoy the well-deserved celebrations, Rory!"
Irish premier Micheal Martin described the win as "epic".
"The Green Jacket is yours Rory McIlroy," the Taoiseach posted on X.
"A finish for the ages at Augusta to win The Masters and complete a richly-deserved career Grand Slam. Epic achievement by one of golf's greatest talents."
Deputy First Minister Emma Little-Pengelly said she was "absolutely delighted" for McIlroy.
"This is an incredible achievement and he truly has made Northern Ireland proud of the international stage," she posted.
"The way he held his nerve to win it and finally get the green jacket, and to complete the career Grand Slam is remarkable."
Ms Little-Pengelly said she was already looking forward to seeing McIlroy on home fairways in the summer when the Open Championship returns to Northern Ireland.
"The reception when he steps onto the first tee at Royal Portrush in July will be incredible," she said.
"Hopefully he can give the home fans plenty to cheer as he bids to win a second Open Championship."
Northern Ireland Secretary Hilary Benn also offered his "huge congratulations" to McIlroy.