Enda Bolger led the tributes to JT McNamara after the former leading amateur jockey died aged 41.
McNamara was paralysed following a fall at the Cheltenham Festival in 2013, when he fractured two vertebrae in his neck when Galaxy Rock came down at the first fence in the Fulke Walwyn Kim Muir Challenge Cup.
Renowned as one of the best amateur riders the sport has ever seen, McNamara partnered more than 600 winners during his career, including four winners at the Cheltenham Festival aboard Rith Dubh (2002 National Hunt Chase), Spot Thedifference (2005 Cross Country Chase), Drombeag (2007 Foxhunter Chase) and Teaforthree (2012 National Hunt Chase).
A minute's silence will be observed before before the 5.45pm at the Galway Races today as a mark of respect.
McNamara enjoyed a special relationship with the Bolger-trained Spot Thedifference, steering the popular gelding to 11 of his 14 victories under Rules, including seven races at Cheltenham.
'More of a horseman than a jockey'
Bolger said: "It's a sad day. He fought a great battle. He was one of those guys who only ever said three words but none would do. He was very unassuming and just a great person to have anything to do with.
"We had a lot of great days together and those are what I'll remember him for. He was an incredible horseman. I would say he was more of a horseman than a jockey."
Dr Adrian McGoldrick, senior medical officer for the Irish Turf Club, confirmed McNamara passed away peacefully during Monday night, just hours after the first day of the Galway Festival, another meeting where he enjoyed success.
McNamara is survived by his wife Caroline and children Dylan, Harry and Olivia.
"I remember him winning the big amateur riders' race on the Flat in Galway and that was a great feather in his cap as riding over fences was really his forte," said Bolger.
"He rode some very good horses in bumpers as well, including Like-A-Butterfly, who went on to win the Supreme Novices' Hurdle.
"He had an unbelievable record in Cheltenham. I think the Kim Muir was the only amateur race he didn't manage to win. He was a great guy and a great jockey and he'll be sorely missed.
"I know the last three years have been hell for him and his family and if there is a heaven, he'll be the first one in, that's for sure."
'So many great days together'
Spot Thedifference, Rith Dubh and Drombeag were among many horses McNamara steered to big-race success for JP McManus.
The leading owner's racing manager, Frank Berry, said: "It's so sad and all our thoughts go out to Caroline and the rest of the family.
"A nicer fellow you couldn't wish to meet. He was in great form up until maybe a week ago and he's definitely been a fighter. He fought a great fight. The boss and him and myself had so many great days together."
'Grumpy enough at times, but was very good-humoured'
Legendary 20-times champion jockey Tony McCoy recalled being in the weighing room at Cheltenham when news of McNamara's accident emerged.
"I remember looking over and seeing his clothes hanging up and thinking 'he'll never be back in here', and that's not something I'll ever forget," McCoy told RTE Radio.
"It's a very sad day for everyone in racing especially his wife Caroline, she's a very tough and amazing woman.
"He was a remarkable man. He was a little bit like me - he could be grumpy enough at times, but was very good-humoured.
"He was fantastic, a brilliant rider. I said this morning that watching his ride on Rith Dubh at the Cheltenham Festival was as good as you'll ever see."
Barry Geraghty, who replaced McCoy as McManus' retained jockey following his retirement, hailed McNamara as a "brilliant fellow".
He said: "It's very sad news and a shock to us all. He was a brilliant fellow. He was a brilliant rider, obviously, but he was such a good, fun person and I suppose he showed his true strength having to deal with this injury over the past few years.
"If you visited him, before you'd know it an hour had passed. The conversation always flowed and there was never any self pity.
"He could hold his own amongst professionals and was better than most. Nothing fazed JT. He was cool as a breeze."
Paralysed from the neck down in fall
McNamara was initially treated in Britain following the Cheltenham fall that left him paralysed from the neck down before being transferred to the spinal unit of the Mater Hospital, Dublin and eventually moving to the North West Regional Spinal Injuries Centre in Southport.
He eventually returned to his native Co Limerick home last June and had begun to establish a training operation at his Croom yard, although he required constant care.
Former leading jockey Mick Fitzgerald was forced to retire from the saddle after suffering serious neck injuries in a fall from L'Ami in the 2008 Grand National at Aintree.
He told At The Races: "The only thing I can say about him is he was a real fighter. That fall that he had, many people thought he would never recover from it, but he defied everybody.
"He's a real inspiration to a lot of people. Every time I think about him, it makes me smile and I think that's the greatest thing you can say about anybody. It makes me realise how lucky I am.
"All he ever wanted was to be there for his family and he just loved being home. The greatest thing of all is he was able to do that for the last (part) of his life. It breaks my heart to think of his family, as this will be a tough time for them.
"I'm just privileged to have known him."
Frankie Ward, regional secretary of point-to-points in Limerick, knew McNamara from a young age and followed his career from ponies to racecourses.
"He was a hero, there's no doubt about it. He was a legend in his own lifetime even though it was a short one," she told Newstalk radio.
"We will all miss him desperately. His colleagues at Galway today will be devastated, but let's celebrate his wonderful life because that's what we should be doing.
"And I'm sure God has probably got him as first jockey up there this morning."
The Mayor of the City and County of Limerick. Cllr Kieran O’Hanlon. also paid tribute to the Croom jockey.
“John Thomas was an inspiration to the people of Limerick and beyond in the way he coped with his life changing injuries following the horrific fall he sustained in Cheltenham in March 2013,” he said.
“Our thoughts are with his wife Caroline and children Dylan, Harry and Olivia at this time. They have lost a wonderful husband and father, in addition to the racing world losing one of its own.”
Minister of State for Tourism and Sport, Patrick O’Donovan TD, also offered his condolences to the family of the jockey.
"A proud Limerick man, JT has been an inspiration to us all in the very dignified and courageous way he adapted to his vastly changed circumstances following his devastating fall in 2013," he said.
"He will be fondly remembered and sadly missed by everyone in the horse racing community and beyond."