William Peter Mullins, Irish racehorse trainer and former jockey, is born on September 15, 1956, in Goresbridge, County Kilkenny. He is a nineteen-time Irish National Hunt Champion trainer and is the most successful trainer in the history of the Cheltenham Festival, having saddled 113 winners as of 2025. He is the trainer of the 2024 Grand National winner “I Am Maximus” and 2025 Grand National winner “Nick Rockett.”

Mullins is born and raised around horses. His father, Paddy Mullins, is a horse trainer, and his mother, Maureen, is a successful breeder.

Although born in Goresbridge, Mullins is based at Closutton, Bagenalstown, County Carlow. He is educated at Cistercian College, Roscrea, an all-boys Catholic boarding school in County Offaly.

Mullins commences racehorse training in 1988, having previously worked as an assistant to his father and Jim Bolger. He is a former six-time amateur champion jockey in Ireland, winning the 1983 Foxhunters’ Open Hunters’ Chase on “Atha Cliath” at the Aintree Racecourse and the 1996 Champion Bumper on “Wither Or Which” at Cheltenham Racecourse.

Mullins is the trainer of the 2005 Grand National winner “Hedgehunter” and the 2011 and 2013 Champion Hurdle winner “Hurricane Fly.” He also trains “Vautour” in the 2016 Ryanair Chase. He is also trainer of the six-time David Nicholson Mares’ Hurdle champion, “Quevega.” In the 2015 Cheltenham Festival, he trains eight winners, a joint record at the Cheltenham Festival which Gordon Elliott equals in 2018. He is the leading-most winning trainer at the Cheltenham Festival, becoming the first trainer to saddle 100 winners when “Jasmin De Vaux” wins the 2024 Champion Bumper. In 2022, he trains a new record of ten winners at the festival.

Mullins’ longlasting relationship with Gigginstown House Stud comes to an end on September 28, 2016. Despite this he is the Irish Champion trainer in the 2016/17 season.

Mullins wins both the 2005 Grand National with “Hedgehunter” and the 2019 Irish Grand National with “Burrows Saint,” each of which is ridden by Ruby Walsh. In the 2022/23 season he becomes Irish National Hunt Champion trainer for the 17th time.

Mullins wins the British jump racing Champion Trainer title in the 2023–24 season, becoming the first trainer based in Ireland to win the championship since Vincent O’Brien in 1954. He successfully defends his title in 2024-25, beating long-time leader Dan Skelton on the last afternoon of the National Hunt season.

Mullins son, Patrick, is an amateur jockey riding mainly in Ireland for his father and acting as assistant trainer to him. Patrick rides “Nick Rockett” to the 2025 Grand National title. Mullins’ wife, Jackie, is a successful amateur rider. With his wife, he is invited to ride in the King’s procession at Royal Ascot 2023.