The author of at least 19 novels, many of them best-sellers, as well as dozens of short stories, essays and plays, Vonnegut relished the role of a social critic.
He lectured regularly, exhorting audiences to think for themselves and delighting in barbed commentary against the institutions he felt were dehumanising people.
"I will say anything to be funny, often in the most horrible situations," Vonnegut once told a gathering of psychiatrists.
Despite his commercial success, Vonnegut battled depression throughout his life, and in 1984, he attempted suicide with pills and alcohol, joking later about how he botched the job.
Critics ignored him at first, then denigrated his deliberately bizarre stories and disjointed plots as haphazardly written science fiction. But his novels became cult classics, especially Cat's Cradle in 1963, in which scientists create "ice-nine", a crystal that turns water solid and destroys the earth.
Many of his novels were best-sellers. Some also were banned and burned for suspected obscenity.
Vonnegut took on censorship as an active member of the PEN writers' aid group and the American Civil Liberties Union. The American Humanist Association, which promotes individual freedom, rational thought and scientific scepticism, made him its honorary president.
Vonnegut once said that of all the ways to die, he would prefer to go out in an airplane crash on the peak of Mount Kilimanjaro. He often joked about the difficulties of old age.
"When Hemingway killed himself, he put a period at the end of his life. Old age is more like a semicolon," Vonnegut told The Associated Press in 2005.