Mr Finlay said: "In over 70 books, Terry enriched the planet like few before him. As all who read him know, Discworld [his fantasy flat disc balanced on the backs of four elephants which stand on the back of a giant turtle] was his vehicle to satirise this world; he did so brilliantly, with great skill, enormous humour and constant invention.
My favorite @terryandrob quote: "Give a man a fire and he's warm for a day, but set fire to him and he's warm for the rest of his life."
— Harry Dresden (@HarriedWizard) March 12, 2015
"Terry faced his Alzheimer's disease (an 'embuggerance', as he called it) publicly and bravely. Over the last few years, it was his writing that sustained him. His legacy will endure for decades to come. My sympathies go out to Terry's wife Lyn, their daughter Rhianna, to his close friend Rob Wilkins, and to all closest to him."
Sad to hear of Sir Terry Pratchett's death, his books fired the imagination of millions and he fearlessly campaigned for dementia awareness.
— David Cameron (@David_Cameron) March 12, 2015
Sir Terry's thousands of fans on Twitter were alerted to the news by a series of messages on Thursday afternoon. The messages read: "AT LAST, SIR TERRY, WE MUST WALK TOGETHER. Terry took Death's arm and followed him through the doors and on to the black desert under the endless night…"
The End.
— Terry Pratchett (@terryandrob) March 12, 2015
Alzheimers and Assisted Suicide
Four years ago, Sir Terry featured in a documentary about suicide in which he followed a man with motor neurone disease to the Dignitas clinic in Switzerland to see him take a lethal dose of barbiturates.
Asked why he wanted to make the film, he said it was because he was "appalled" at the state of the law. He said: "The Government here has always turned its back on it and I was ashamed that British people had to drag themselves to Switzerland, at considerable cost, in order to get the services that they were hoping for.''
Hilary Evans, director of Alzheimer's Research UK, said the death of Sir Terry would have "a profound effect on both literature and the 850,000 people who live with dementia".
We are very sad to hear that Sir Terry Pratchett has died after a long battle with Alzheimer's — read our statement: http://t.co/E74DSTHOPS
— Alzheimer's Society (@alzheimerssoc) March 12, 2015
She said his announcement of his own diagnosis was "a watershed moment" and "a call to arms for society to talk about dementia and take steps towards defeating it".
DON’T THINK OF IT AS DYING, said Death. JUST THINK OF IT AS LEAVING EARLY TO AVOID THE RUSH. – TERRY PRATCHETT (1948-2015)
— The QI Elves (@qikipedia) March 12, 2015