One of the world’s most renowned fantasy authors Sir Terry Pratchett has passed away at age 66. The beloved British writer had been struggling with Alzheimer’s Disease since being diagnosed almost eight years ago.

“I was deeply saddened to learn that Sir Terry Pratchett has died. The world has lost one of its brightest, sharpest minds,” said Larry Finlay of his publisher Transworld Books in a statement. The author passed away at his home in England, surrounded by family, “with his cat sleeping on his bed,” he added.

Sir Terry wrote over 70 books throughout his 44-year career. His works are popular across the globe and have been translated into 37 different languages. The author completed his final novel last summer.

The final tweets from his official Twitter account were a wonderful, poignant nod to the characters he helped create:

AT LAST, SIR TERRY, WE MUST WALK TOGETHER.

— Terry Pratchett (@terryandrob) March 12, 2015

Terry took Death’s arm and followed him through the doors and on to the black desert under the endless night. — Terry Pratchett (@terryandrob) March 12, 2015

The End.

— Terry Pratchett (@terryandrob) March 12, 2015

The first book in his famous Discworld series, “The Colour of Magic,” was published in 1983. Set in the fictional Discworld, a flat disc set upon the backs of four elephants that ride a gigantic turtle, the series brilliantly blended mythology with the satirization of current affairs. More than 80 million books have been sold worldwide. Additionally, Sir Terry is also known for his wonderful apocalypse comedy Good Omens, co-written with Neil Gaiman.

Sir Terry was granted numerous accolades for his work over the years. He was appointed an Officer of the Order of the British Empire in 1998 and knighted for his services to literature in the 2009 New Year Honours. The first Discworld book geared towards children, “The Amazing Maurice and his Educated Rodents”, won the annual Carnegie Medal in 2001. Additionally, he received the World Fantasy Award for Life Achievement in 2010.

The author worked hard to bring attention to Alzheimer’s Disease in the years after his diagnosis. In partnership with the BBC, he filmed a two-part documentary chronicling his illness. Sir Terry also worked hard to increase funding for dementia research. A Just Giving page has been set up in his memory with all funds going to the Research Institute to the Care of Older People (RICE) for all those wishing to donate.

Sir Terry will be missed, but his work will live on through readers everywhere. As one of my favorite Discworld quotes goes, “No-one is finally dead until the ripples they cause in the world die away… The span of someone’s life, they say, is only the core of their actual existence.”