Dr. Jack Kevorkian, the medical pathologist who helped dozens of terminally ill people kill themselves, becoming the central figure in a national drama surrounding assisted suicide, died on Friday in a Detroit-area hospital. He was 83.

The cause was not immediately known, but local media reported that he had suffered from kidney and respiratory problems and that his condition had been worsening in recent days. His death, at William Beaumont Hospital in Royal Oak, Mich., was confirmed by Geoffrey Feiger, the lawyer who represented Dr. Kevorkian during several of his trials in the 1990s.

Dr. Kevorkian challenged social taboos about disease and dying, willfully defying prosecutors and the courts as he actively sought national celebrity. He spent eight years in prison after being convicted of second-degree murder in the death of the last of the more than 100 terminally ill patients whose lives he helped end....