Explorer Henry Worsley has died after suffering extreme dehydration, and exhaustion during an attempt to cross Antarctica.
The former Army office, who was 55, was 71 days into his epic bid to become the first person in history to cross the Antarctic unaided and unassisted.
In a statement, his wife Joanna said she felt "heartbroken sadness." Henry Worsley, from Fulham in London, died of "complete organ failure", she added.
On Instagram, David Beckham said he was "lucky to have met Henry", who "served our country for so many years."
The ex-footballer added that "No words can describe the sadness of the loss of Henry."
Despite the best efforts of staff at the Clinica Magallenes in Punta Arenas, Chile, Mr Worsley failed to recover from his critical state.
Henry Worsley started the 80-day, 1100-mile coast-to-coast trek in November. He was pulling a sledge containing his food, tent and equipment.
The plan was to cross the continent with no supply drops, and without help from dogs or any other animal.
Worsley was aiming to raise £100,000 for the Endeavour Fund, which aids sick and injured servicemen and women.
When asked about the expedition, and how he planned to stay motivated during it, Worsley said: "What will drive me on is raising money for these wounded soldiers."
Our thoughts are with Henry's friends and family at this difficult time.