He was elected to the Science Fiction and Fantasy Hall of Fame in 2004, and five years later the Science Fiction Writers of America gave him its Damon Knight Memorial Grand Master Award.

He was born Henry Maxwell Dempsey on March 12, 1925, in Stamford, Conn. His father, Henry, changed their last name to Harrison soon after Harry’s birth. Harry did not find out until he applied for a passport, at 30, that his last name was still Dempsey. He then changed it to Harrison, except when using Dempsey as a pseudonym.

After finishing high school he was drafted into the Army, where he repaired gunsight computers and developed a hatred of the military that inspired much of his later writing. He studied art in New York, then worked as an illustrator and writer for pulp magazines. He wrote scripts for comic strips, including “Flash Gordon.” In the 1950s he began writing science fiction full time.

For years Mr. Harrison, who found inspiration in the sardonic humor of Voltaire, could not find a publisher for an early story he wrote, “The Streets of Ashkelon,” about an atheist who tries to protect the inhabitants of an alien world from the influence of a Christian missionary. It was eventually anthologized in the United States and translated into Swedish, Italian, Russian, Hungarian and French.

In another story, the Stainless Steel Rat’s homicidal wife, Angelina, gave birth to twins who ended up marrying the same woman — after she had herself duplicated, becoming two identical women sharing one mind. Mr. Harrison’s own wife, of 48 years, the former Joan Merkler, died in 2002. His survivors include his children, Todd and Moira.

The Harrison family moved often and far, living in Mexico, Ireland, Italy, Denmark, the United States and finally England. But Mr. Harrison preferred a world with no boundaries, and for that reason championed Esperanto, the artificial international language. He claimed, apparently with no dispute, to have written the only science-fiction story in Esperanto.