Sir Nicholas Winton, who organised the rescue of nearly 700 Jewish children from Nazi-occupied Czechoslovakia, has died in hospital at the age of 106.
Sir Nicholas was nicknamed Britain's Schindler after he saved the lives of 669 children by sending them on trains from Prague to London.
His son-in-law Stephen Watson said Sir Nicholas died peacefully in his sleep at Wexham Hospital in Slough.
Prime Minister David Cameron described Sir Nicholas as a "great man", adding: "We must never forget Sir Nicholas Winton's humanity in saving so many children from the Holocaust."
Sir Nicholas organised eight trains from Prague to London to rescue children he feared would be sent to Nazi-run concentration camps.
He also helped to find foster families for the children once they arrived in England. He did not reveal his actions during the war for half a century.
Sir Nicholas was knighted in 2003 and received a Hero of the Holocaust medal at Downing Street in 2010.
A statement from the Rotary Club of Maidenhead, of which Sir Nicholas was a member, said: "It is with much sadness I have to report that Sir Nicky Winton died peacefully early this morning.
"Nicky's daughter Barbara and two grandchildren were with him when he died and Barbara said that he was aware of their presence."
Last year, after being awarded the Order Of The White Lion by Czech president Milos Zeman at a ceremony in Prague, Sir Nicholas thanked the British people for welcoming the children.
"I thank the British people for making room for them, to accept them, and of course the enormous help given by so many of the Czechs who at that time were doing what they could to fight the Germans and to try and get the children out," Sir Nicholas said.
"In that respect, I was of some help and this is the result."
Home Secretary Theresa May, Maidenhead's MP, said Sir Nicholas was a "hero of the 20th century".
"Against the odds, he almost single-handedly rescued hundreds of children, mostly Jewish, from the Nazis - an enduring example of the difference that good people can make even in the darkest of times.
"Because of his modesty, this astonishing contribution only came to light many years later. So many people owe their lives to Nicholas and it was fitting that, in his later years, he finally received the recognition he deserved.
"Maidenhead is rightly proud of all that he did, and we must ensure that his legacy lives on by continuing to tackle anti-Semitism and discrimination wherever it arises."