LONDON — Novelist Terry Pratchett, best known for the comic fantasy series “Discworld,” has died at the age of 66.

Pratchett, who was diagnosed with Alzheimer’s disease in 2007, wrote more than 70 books over his career.

“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 humor and constant invention,” Transworld Publishers’ Larry Finlay told the BBC.

Pratchett, who started out as a journalist, published his first novel, “The Carpet People,” in 1971. It received rave reviews. This was followed by sci-fi novels “The Dark Side of the Sun,” in 1976, and “Strata,” in 1981.

Two years later, he published “The Color of Magic,” the first of what would become the “Discworld” series.

“The nature of ‘Discworld’ gave me the opportunity to do all kinds of things,” he said. “I could fit more or less anything into it. By about book four, I discovered the joy of plot.”

By 2013, “Discworld” had grown to encompass 40 novels, although Pratchett also wrote horror fiction and children’s books. He completed his last book, a new Discworld novel, in the summer of 2014.

Many of his stories were adapted for the stage and TV, including “Hogfather,” “Wyrd Sisters” and “Soul Music.”

After the Alzheimer’s diagnosis in 2007, Pratchett campaigned on behalf of charities researching the disease, and he made a two-part documentary for the BBC, “Living with Alzheimer’s,” in which he discussed its effect on his life. He also became an advocate for assisted suicide, and introduced the BBC documentary “Terry Pratchett — Choosing to Die.”

Pratchett leaves his wife, Lyn, and their daughter, Rhianna.