The broadcaster and writer Sir David Frost has died from a suspected heart attack the age of 74, according to his family.
"Sir David died of a heart attack last night aboard the Queen Elizabeth which is a Cunard (cruise) liner where he was giving a speech.
"His family are devastated and ask for privacy at this difficult time."
Sir David's career spanned journalism, comedy and television presenting, notably on the BBC.
Internationally, he was best known for his famous interviews with former US President Richard Nixon in 1977, dramatised as a Hollywood movie "Frost/Nixon" in 2008.
He had continued working as a TV host on the Al Jazeera English channel up to his death.
British prime minister David Cameron said: "Sir David was an extraordinary man - with charm, wit, talent, intelligence and warmth in equal measure. He made a huge impact on television and politics.
Sinn Féin president Gerry Adams TD also expressed his sadness and condolences.
"I was interviewed by David many times. He was always courteous, good humoured, well-researched and keenly interested in Ireland and the peace process.
"There was always a depth to his interviews that is frequently missing in others."
"Consequently he was the master of the great interview," said Mr Adams.
"David's style of interview was unique and effective. He once explained to me that there are two types of interview. One in which the interviewer attacks like a blizzard, a storm, and the response of the guest is to button up, put on the big overcoat and go into protective mode," added the Sinn Féin leader.
"The other is to come at the guest like a sunny day. This encourages the guest to take off their jacket and relax. In this way you get the more informed and interesting interview."
Mr Cameron said he was both fearsome and a friend.
"The Nixon interviews were among the great broadcast moments - but there were many other brilliant interviews. He could be - and certainly was with me - both a friend and a fearsome interviewer," said the British leader.
Sir David's list of interviewees include virtually every US president and British prime minister during his working life.
Others included Robert F Kennedy, Henry Kissinger, Pierre Trudeau, Mikhail Gorbachev, Indira Gandhi, Benazir Bhutto, King Hussein, Golda Meir, Yasser Arafat, Yitzhak Rabin, Nelson Mandela, FW de Klerk, Prince Charles, the Duke and Duchess of York, the Princess Royal and countless more.
He was the only person to have interviewed all six British prime ministers serving between 1964 and 2007 (Harold Wilson, Edward Heath, James Callaghan, Margaret Thatcher, John Major and Tony Blair) and the seven US presidents in office between 1969 and 2008 (Richard Nixon, Gerald Ford, Jimmy Carter, Ronald Reagan, George HW Bush, Bill Clinton and George W Bush). He was also the last person to interview Mohammad Reza Pahlavi, the last Shah of Iran.
Outside world affairs, his roster ranged from Orson Welles, Tennessee Williams, Noel Coward, Peter Ustinov, Woody Allen, Muhammad Ali, the Beatles, Clint Eastwood, Sir Anthony Hopkins, Sir John Gielgud, Norman Mailer, Warren Beatty and many more.
Sir David won virtually all the major television awards available.
Sir David first came to notice in Britain with the Saturday night TV satirical programme That Was The Week That Was, which he hosted and co-created in the early 1960s.