Prince Philip, whose retirement from public duties was announced Thursday, has been Queen Elizabeth II's loyal husband for almost 70 years but has often hit the headlines for his salty off-the-cuff comments.
The 95-year-old Duke of Edinburgh is patron, president or a member of almost 800 organisations, and has accompanied his wife on countless British and overseas engagements.
Five years ago he said he believed he had "done his bit", and now, despite continued robust health, he has decided to step back altogether.
Prince Philip has been by the queen's side since their marriage in 1947, before she became monarch.
They share a sense of duty and tradition as well as a great-great-grandmother, queen Victoria.
In a 1997 speech marking their golden wedding anniversary, she said he has, "quite simply, been my strength and stay all these years".
He has stolen the limelight more than a few times with his outspoken remarks, some of them embarrassingly politically incorrect gaffes.
"You managed not to get eaten, then?" was one typical remark to a British student who had trekked in Papua New Guinea in 1998.
"Still throwing spears?" he asked an Australian Aborigine during a 2002 visit.
But observers say his quips put people at ease -- while also providing a welcome contrast to the queen's seriousness.
- 'My first duty' -
Philip met the then Princess Elizabeth just before the outbreak of World War II, and they exchanged letters while he served with the Royal Navy in the Mediterranean and the Pacific.
After their marriage, they spent time in Malta, where he was posted -- only for their lives to be changed overnight by the premature death of her father, king George VI, in 1952.
He once admitted the curtailment of his promising naval career was "disappointing", but said that "being married to the queen, it seemed to me that my first duty was to serve her in the best way I could".
Although he had a reputation for coldness towards his children, many observers consider Philip the glue that held the royal family together as their offspring went through a series of divorces in the 1990s.
In a rarely seen softer side to the prince, it emerged that the late Diana, princess of Wales addressed him as "Dearest Pa" in letters in which he offered solace over her deteriorating marriage to his eldest son Prince Charles.
He has also been credited for the way he tried to protect Charles and Diana's sons, Princes William and Harry, from media attention following Diana's death in 1997.
- 'I've done my bit' -
In a rare interview to mark his 90th birthday in 2011, the prince said he carved out his role by "trial and error".
"There was no precedent. If I asked somebody, 'What do you expect me to do?' they all looked blank. They had no idea," he told the BBC.
Philip has a keen interest in scientific and technological research, and was also an early champion of the conservation movement.
He served as the first president of the British branch of the World Wildlife Fund from its foundation in 1961 to 1982.
Many of his charities also involve young people, including the Duke of Edinburgh's Award, a scheme to build life skills that has been completed by more than eight million young people since 1956.
Philip was born on a kitchen table on the Greek island of Corfu on June 10, 1921, the only son of prince Andrew of Greece -- the younger brother of Greece's king Constantine I -- and princess Alice of Battenberg.
Aged just 18 months, his family were evacuated on a British navy ship from politically unstable Greece, with the infant reputedly carried in a cot made from an orange box.
They settled in Paris, and at seven Philip was sent away to school in England.
He became a Royal Navy cadet following the outbreak of war in 1939. By 1945, he was a first lieutenant and was in Tokyo Bay for the Japanese surrender.
When he married he gave up his titles as a prince of Greece and Denmark -- and became a naturalised British subject.
In 2011, he said: "I reckon I've done my bit so I want to enjoy myself a bit now.
"It's better to get out before you reach the sell-by date."