Sprinter Sacre has been retired, his trainer Nicky Henderson has announced.
The 10-year-old was one of the best two-mile chasers ever, winning the Queen Mother Champion Chase at Cheltenham in 2013 and in heart-warming scenes again last March.
After suffering from a fibrillating heart in December 2013, he was nursed back to his best by Henderson to rule to two-mile division once more.
Henderson tweeted: "It is with deep regret that I have to announce the sad news that Sprinter Sacre has been retired. He was the horse of an absolute lifetime."
The Seven Barrows handler said at a media conference at Cheltenham racecourse on Sunday that the decision to retire Sprinter Sacre was made after he developed leg injury earlier in the week.
Henderson added: "We're going to miss him. It has been a great journey and he's been a big part of our lives.
"It's been a pretty emotional time over the past five or six years and we've loved every moment of it, but all good things have to come to an end."
Sprinter Sacre will today parade before Shloer Chase, a race he brilliantly last year, at Cheltenham.
Sprinter Sacre won 18 of his 24 starts and amassed £1,136,000 in prize-money.
In between his two Champion Chase victories, however, he was plagued with problems before returning to something approaching his best last season.
Joining the Henderson stable from France, he made a winning debut in an Ascot bumper in February 2010 and went novice hurdling the following campaign.
After winning two of his first three starts, he was then third in the Supreme Novices' Hurdle in March 2011.
It was a chaser he really made his mark, though.
He created a big impression in his novice season which saw him defeat Cue Card in the Arkle Trophy in 2012.
Sprinter Sacre went on to win his first 10 races over fences, including the Champion Chase at the 2013 Cheltenham Festival.
But his successful streak came to an abrupt halt when he was pulled up in the Desert Orchid Chase at Kempton that December, after which it transpired he had an irregular heartbeat.
He made a full recovery and returned to action in January 2015 when he was second to Dodging Bullets in the Clarence House Chase at Ascot.
But when he was pulled up in that season's Champion Chase it seemed his best days were behind him.
However, he came back in tremendous form last season and after wins in the Shloer Chase and the Desert Orchid Chase, Sprinter Sacre reclaimed his two-mile crown with a convincing defeat of Un De Sceaux at the Festival in March.
He wound up the campaign with a similarly authoritative victory in the Celebration Chase at Sandown in April in what turned out to be his swansong.
Explaining Sprinter Sacre's career-ending injury, Henderson said: "It all crept up yesterday. He worked on Tuesday and everything was grand.
"We were just a bit worried on Wednesday night as he was warm in one leg. I was going to work him yesterday but we couldn't work him.
"We can't ask him to come back, not at his age.
"He's in the same stable he has always spent his days in here (at Cheltenham) and you wouldn't know which leg I was talking about.
"In fact, if I was thinking about working this afternoon him I would.
"It (the injury) wouldn't hold up in the short term and when you can't go for the long term, you have to sadly bite the bullet."