One of the brightest fantasy authors and "Discworld" creator, Terry Pratchett has died at the age of 66, eight years after he was diagnosed with Alzheimer's disease.

Pratchett, who was knighted in 2009, is "an accomplished satirist with a penchant for sending up cultural and political tomfoolery" according to The New York Times. His books, which were noted to have stinging references to different genres, have sold over 85 million copies.

The announcement of his death was made on his Twitter account through a tweet that says, "Terry took Death's arm and followed him through the doors and on to the black desert under the endless night." Later on, her daughter Rhianna wrote on her microblogging site, "Many thanks for all the kind words about my dad. Those last few tweets were sent with shaking hands and tear-filled eyes."

According to Larry Finlay of Transworld Publishers, the author died in his home in England, surrounded by his family, and "with his cat sleeping on his bed".

Finlay said in a statement published on Pratchett's website, "I was deeply saddened to learn that Sir Terry Pratchett has died. The world has lost one of its brightest, sharpest minds."

According to the Los Angeles Times, Pratchett has authored over 70 books and won numerous awards for his works, one of which is a Los Angeles Times Book award in 2008 for his novel, "Nation."

However, he was best known for his work in the "Discworld" series, the last one published last year, called "Raising Steam." The series began in 1983 with "The Colour of Magic" and is set in a fantasy universe of characters living on a flat disk perched on the back of several elephants.

To date, there are 40 installments to the series, and Pratchett was considered the most successful author in Britain before the explosion of JK Rowling's "Harry Potter" novels.

Neil Gaiman, famed British author and co-author to the satirical "Good Omens" with Pratchett, shared his condolences via his blog on Thursday, saying, "Thirty years and a month ago, a beginning author met a young journalist in a Chinese Restaurant, and the two men became friends, and they wrote a book, and they managed to stay friends despite everything. Last night, the author died. There was nobody like him. I was fortunate to have written a book with him, when we were younger, which taught me so much."

BBC also noted that a fundraising site has been set up in Pratchett's memory in an effort to raise money for a charity that takes care of those with Alzheimer's.