Getty Images News Terry Pratchett, the 66-year-old author best known for the "Discworld" fantasy series, has died.

Pratchett had suffered from early-onset Alzheimer's disease for several years before his death, which he spoke about publicly frequently.

The author of more than 70 books throughout his lifetime, he was given an OBE in 1998 and knighted in 2009. He won multiple literary awards, including the Carnegie Medal and the World Fantasy Award for Lifetime Achievement in 2010.

His last book was completed in the summer of 2014.

Pratchett was hugely beloved by readers around the world. His Discworld series told the ongoing saga of a fictional "Discworld," resting on the backs of four giant elephants, themselves standing on top of a enormous turtle swimming through space. The dozens of books in the series followed a diverse array of characters, including inept wizard Rincewind, an anthropomorphic Death, a coven of witches, and Sam Vines, commander of the "City Watch" in the city of Ankh-Morpork.

The 41 Discworld books have been adapted into other mediums multiple times — notably a Sky One production of "Hogfather," audio books, 15 stage adaptations, and two point-and-click adventure video games.

The author was also a passionate advocate for the legalisation of voluntary euthanasia, and made a 2011 documentary on the subject.

According to a statement from his publisher Transworld Publishers , Pratchett "passed away in his home, with his cat sleeping on his bed surrounded by his family" earlier today. He is survived by his wife Lyn, and his daughter Rhianna.

Larry Finlay, Managing Director of Transworld Publishers, said he was "deeply saddened to learn that Sir Terry Pratchett has died. The world has lost one of its brightest, sharpest minds."

A Just Giving page donating to the Research Institution to the Care of Older People (RICE) has been set up in Pratchett's memory. As of writing, it had raised just over £7,200, and is rising fast.

Here are the last tweets sent from his official Twitter account:

Here's the full statement from Pratchett's publisher:

I was deeply saddened to learn that Sir Terry Pratchett has died. The world has lost one of its brightest, sharpest minds.

In over 70 books, Terry enriched the planet like few before him. As all who read him know, Discworld was his vehicle to satirize this world: he did so brilliantly, with great skill, enormous humour and constant invention.

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."

Terry passed away in his home, with his cat sleeping on his bed surrounded by his family on 12th March 2015. Diagnosed with PCA1 in 2007, he battled the progressive disease with his trademark determination and creativity, and continued to write. He completed his last book, a new Discworld novel, in the summer of 2014, before succumbing to the final stages of the disease.

We ask that the family are left undisturbed at this distressing time."

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