Former Liberal Democrat leader Charles Kennedy has died at his home in Scotland aged 55, his family has said.
Mr Kennedy lost his seat in the Ross, Skye and Lochaber constituency to the Scottish National Party's Ian Blackford in last month's general election.
A statement released on behalf of his family said: "It is with great sadness, and an enormous sense of shock, that we announce the death of Charles Kennedy.
"Charles died at home in Fort William yesterday. He was 55. We are obviously devastated at the loss. We ask therefore that the privacy of his family is respected in the coming days.
"There will be a post mortem and we will issue a further statement when funeral arrangements are made."
A spokesman for Police Scotland said: "Police officers attended an address at Fort William on Monday, June 1 to reports of the sudden death of a 55-year-old man. Police were notified by ambulance service personnel.
"There are no suspicious circumstances and our report will be submitted to the procurator fiscal."
An MP since 1983, Mr Kennedy had previously taken the party to its best election result since the 1920s at the 2005 contest.
His political career began in the Social Democratic Party, winning the Ross, Cromarty and Skye seat to become the youngest MP of the time at the age of 24.
The father-of-one was leader of the Liberal Democrats between 1999 and January 2006 - when he stood down days after admitting he had a problem with alcohol.
He took over as leader from Paddy Ashdown in 1999, and in that role was one of the most vocal critics of the invasion of Iraq in 2003.
In the 2005 general election he took the party to what was then one of its best general election results, winning 62 seats.
But just months later, following rumours about his drinking, Mr Kennedy admitted he had been receiving treatment for an alcohol problem and said he was calling a leadership contest.
While he had initially declared that he wanted to carry on he was forced to stand down in the face of the threat of mass resignations by senior colleagues.
Nick Clegg, who stood down as party leader after last month's general election, paid tribute to his predecessor and said: "Charles's untimely death robs Britain of one of the most gifted politicians of his generation.
"He was a staunch internationalist and passionate believer in Britain's role in Europe, yet he was a proud Highlander, Scot and British parliamentarian.
"He was one of the most gentle and unflappable politicians I have ever known, yet he was immensely courageous too not least when he spoke for the country against the invasion of Iraq.
"He led the Liberal Democrats to our party's greatest electoral successes, yet he always remained modest about his huge achievements."
Sad beyond words to hear the news about Charlie Kennedy. A lovely man and one of the most talented politicians of his time. Gone too soon.
— Nicola Sturgeon (@NicolaSturgeon) June 2, 2015I am utterly heartbroken about the news of Charles' passing. He was a colleague, friend and mentor. We've lost a giant today.
— Tim Farron (@timfarron) June 2, 2015 Waking up to the very sad news of the death of former Liberal Democrat Leader Charles Kennedy.His family are in my thoughts & prayers.
— Martin McGuinness (@M_McGuinness_SF) June 2, 2015