Sir Terence David John Pratchett, OBE (born 28 April 1948) is an English novelist, most well known for his long running "Discworld" series of comedy fantasy books. The Discworld books are set on a fantasy world where dragons, trolls, witches, wizards, vampires and gods exist. The books are satirical in nature and echo our own world and parody many people, ideas and institutions. Pratchett has written 36 novels set on Discworld and sold over 55 million copies, they have been translated into 37 different languages and their have been numerous tv, stage and radio adaptations.
In December 2007 he announced that he had been diagnosed with early onset Alzheimer's disease which he described as an "embuggerance". He has spoken out about the lack of funding into Alzheimer's (3% of whats spent on cancer research) and donated a million dollars to the Alzheimer's Research Trust.
In 2011, two prominent discworld characters, Rincewind and Nanny Ogg, were featured on Royal Mail stamps, alongside other fictional magical characters such as Dumbledore from the Harry Potter series.  A Disney adaption of his fourth discworld novel, "Mort" is also being developed.