Many of Pratchett's books have been adapted for stage, TV and radio
The author Terry Pratchett - whose novels have sold millions of copies worldwide - has been made a knight in the New Year Honours list.
The writer, 60, who is best known for his hugely popular Discworld series of comic fantasy novels, received the honour for services to literature.
Sir Terry announced in December 2007 that he had been diagnosed with early-onset Alzheimer's disease.
He has since campaigned to raise awareness of the condition.
Terry Pratchett has sold more than 55 million books worldwide and has had his works translated into 33 languages.
Terry Pratchett on how he feels about his knighthood
Born in April 1948 in Beaconsfield, and educated at High Wycombe Technical High School, Sir Terry sold his first story when he was 13 years old and used the money to buy a second-hand typewriter.
A few years later, in 1971, his first book The Carpet People was published.
It detailed the first of Pratchett's alternative universes, but the most successful has been Discworld - with magical characters living on a flat world sitting on the backs of four elephants, who stand on the shell of a giant turtle.
The first Discworld novel was The Colour of Magic (1983), which Sir Terry wrote in his spare time while working as a press officer.
He turned to writing full time in 1987 after completing his fourth Discworld novel Mort.
First 10 Discworld novels
The Colour of Magic
The Light Fantastic
There are 36 books in the Discworld series.
The first Discworld novel for children, The Amazing Maurice and his Educated Rodents, was published in 2001 and was awarded the Carnegie Medal.
Many of his books have been adapted for stage, TV and radio.
On his official website, Sir Terry says of Discworld: "It started out as a parody of all the fantasy that was around in the big boom of the early '80s, then turned into a satire on just about everything, and even I don't know what it is now.
"I do know that in that time there's been at least four people promoted as 'new Terry Pratchetts' so for all I know I may not even still be me."
Sir Terry has won numerous literary awards, and was made an OBE for services to literature in 1998. He has honorary doctorates from the Universities of Warwick, Portsmouth, Bath and Bristol.
Terry Pratchett talks about the stigma of dementia
In December 2007, the author announced he had been diagnosed with a rare form of early-onset Alzheimer's disease, PCA, which affects the back of the brain and therefore vision and motor skills.
In April, Sir Terry told ITV's This Morning that news of his illness had made him "absolutely angry".
"I didn't know where to go and what to do and there was a lot of flailing around and shouting really," he said.
The writer said: "I'm a humanist, which means I'm an atheist, the trouble with being an atheist is that it lets God off the hook. You really want someone to blame."
He became Patron of The Alzheimer's Research Trust, and has donated nearly £500,000 for research into Alzheimer's.
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