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Ray Bradbury, author of some of science-fiction's classic novels including "Fahrenheit 451? and "The Martian Chronicles," has died. He was 91.

Bradbury's grandson, Danny Karapetian, confirmed his death on Twitter, writing, "The world has lost one of the best writers it's ever known, and one of the dearest men to my heart. RIP Ray Bradbury (Ol' Gramps)."  Karapetian also told the website io9.com, "If I had to make any statement, it would be how much I love and miss him … His legacy lives on in his monumental body of books, film, television and theater, but more importantly, in the minds and hearts of anyone who read him, because to read him was to know him. He was the biggest kid I know."

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Born in Waukegan, Ill., Bradbury ultimately became one of the 20th century's most popular and celebrated science-fiction writers, along with Isaac Asimov, Arthur C. Clarke and Robert A. Heinlein.  Bradbury's literary career spanned 70 years, beginning with short stories published in sci-fi pulp magazines.  A series of such short stories, all of them set on or having to do with Mars, ultimately became his first novel, "The Martian Chronicles."  Published in 1950, it was followed three years later by "Fahrenheit 451," set in a dystopian future world where books are outlawed and firemen burn them.  That novel, named after the temperature at which book paper ignites,  remains perhaps Bradbury's most celebrated work.

Other Bradbury novels include "Something Wicked This Way Comes," and "The Illustrated Man and Dandelion Wine."  He continued to write short stories and essays throughout his career. Bradbury was also a poet, a playwright and a screenwriter, co-writing the screenplay for the 1956 film "Moby Dick" with the film's legendary director, John Huston.

Bradbury's wife of 56 years, Marguerite, died in 2003.