British and Irish Lions captain Sam Warburton has retired from rugby union at the age of 29 after failing to overcome persistent injury problems.
The former Wales captain has not played since leading the 2017 Lions to a drawn series against New Zealand.
"My body is unable to give me back what I had hoped for on my return to training," said Warburton.
"Unfortunately, after a long period of rest and rehabilitation the decision to retire from rugby has been made with my health and wellbeing as a priority."
Warburton emulated England World Cup-winning skipper Martin Johnson in captaining the Lions on two separate tours.
Under his leadership, the Lions claimed a first Test series victory for 16 years when they beat Australia, and then drew the series against New Zealand a year ago.
49 - Sam Warburton captained Wales on 49 occasions, more than any other player, while he is also one of just two players to captain the Lions on two tours (also Martin Johnson). Skipper. 🏴🦁 pic.twitter.com/oJ63xt08uR— OptaJonny (@OptaJonny) July 18, 2018
He also steered Wales to the 2011 World Cup semi-finals - he was controversially sent off in the last-four clash against France - with Gatland appointing him as Wales skipper and Lions leader, after heading up the Australia and New Zealand tours as coach.
Gatland said: "It is hugely disappointing that Sam has retired from the game.
"He is an outstanding rugby player and he has brought so much to the game, on and off the pitch.
"His leadership, attitude and demeanour, along with his performances, have placed Sam up there as one of the best and most respected players in the world.
"He finishes with a record that he should be extremely proud of and should look back on his career with huge pride."