John Calder, an influential British publisher who championed avant-garde authors and battled censorship, died Aug. 13 at a hospital in Edinburgh, Scotland. He was 91.

The death was confirmed by Alessandro Gallenzi of Alma Books. The cause was not disclosed.

Mr. Calder, who was born in Montreal, worked in the family timber business before founding the London-based Calder Publications in 1949. It published classic European writers including Anton Chekhov, Leo Tolstoy and Emile Zola, as well as modern authors — notably Samuel Beckett, whom Mr. Calder considered “the greatest of 20th-century writers.”

Mr. Calder published much of Beckett’s nontheatrical work — novels, poems and essays — and wrote several books about the Nobel Prize-winning Irish writer. The pair remained close friends until Beckett’s death in 1989.

Mr. Calder also helped introduce British readers to continental writers including Eugene Ionesco, Marguerite Duras and Alain Robbe-Grillet, and championed edgy Americans, publishing Henry Miller’s “Tropic of Cancer” and William S. Burroughs’s “Naked Lunch.”

In 1966, Mr. Calder was convicted of obscenity for publishing Hubert Selby’s gritty novel “Last Exit to Brooklyn.” The conviction was overturned on appeal, in a landmark free-speech case.

Mr. Calder also ran unsuccessfully for Parliament, campaigned against nuclear weapons, organized a music and opera festival at his Scottish mansion and ran an idiosyncratic London book store, Calder Books.

Calder Publications was sold after his retirement to Alma Books, which said Mr. Calder had published 1,500 books, including works by 18 Nobel Prize winners.

Gallenzi of Alma Books called Mr. Calder “a towering figure in the fight against censorship and the dissemination of international literature and culture in the U.K.”

“His influence — as a publisher, as an author, as an intellectual and as a beacon for an entire generation of readers and writers — cannot be underestimated,” Gallenzi said.