"It is the duty of every honest person to write the truth about Stalin," Anton Antonov-Ovseyenko, a Soviet historian and dissident, wrote in the preface of his seminal book "The Time of Stalin: Portrait of a Tyranny," published illegally in 1981.
A survivor of the gulag whose parents died in Stalin's purges, Mr. Antonov-Ovseyenko spent a lifetime in almost fanatical devotion to that duty, working until his death on Tuesday in Moscow at 93 to expose the darkest truths of the Soviet era.
His books cracked through the shell of Soviet censorship that surrounded much of the Stalin-era brutality, offering readers at home and in the West a vivid portrait of tyranny and violence.
Mr. Antonov-Ovseyenko's death comes as attitudes toward Stalin in Russia have grown increasingly ambivalent. Russian leaders these days tend to praise his leadership during World War II, often overlooking the tens of millions killed during his rule.
Mr. Antonov-Ovseyenko founded the State Museum of the History of the Gulag in Moscow in 2001 as a repository of artifacts from the Stalin era. Although it is rarely visited, Roman Romanov, his protégé and the current museum director, said in a telephone interview that Mr. Antonov-Ovseyenko worked there until the end, spending two full days a week at the museum and helping with a planned expansion into a new and larger space.
Anton Vladimirovich Antonov-Ovseyenko was born in Moscow on Feb. 23, 1920, to a family with an impeccable revolutionary pedigree. His father, Vladimir Antonov-Ovseyenko, was a famous Soviet military commander who led the assault on the Winter Palace in St. Petersburg (it was then Petrograd) in November 1917, helping to usher in more than 70 years of Soviet rule.
Stalin's rise to power at the end of the 1920s upended the family's fortunes and set Mr. Antonov-Ovseyenko on the path to becoming a dissident. He parents were accused of being counterrevolutionaries and arrested. His mother, Rozalia, committed suicide in prison in 1936. His father was executed in 1938.
As the son of convicted state enemies, Mr. Antonov-Ovseyenko was himself arrested in 1940. He spent the next 13 years in and out of the Soviet gulag, an experience that made him a lifelong opponent of the Soviet government.
In a 2011 interview with the Public Radio International program "The Word," he recounted being forced by a prison guard at gunpoint to read a speech by Stalin over the prison radio.
"I had to read the words of the person who was my enemy, and I was an enemy of the state," he said.
He was released after Stalin's death in 1953. Though almost completely blind, he began working in the Soviet archives in Russia. His first book, published under a pseudonym, was a biography of his father, who had been rehabilitated during the political thaw under Nikita S. Khrushchev. He went on to write several other books, most of them about Stalin and his associates.
Perhaps his most influential work was "The Time of Stalin," the first book published under his own name, which was smuggled out of Moscow and published in New York in 1981. Copies were then smuggled back in and disseminated among the underground dissident salons of Moscow.
"The Time of Stalin" was among the first books to unmask the horror of the Stalin era, putting the death count through years of civil war, famine, purges and World War II in the tens of millions. Harrison E. Salisbury, who won a Pulitzer Prize for his reporting in Moscow for The New York Times in the 1950s, called the book "a milestone toward the understanding of three-quarters of a century of Russian trauma."
Mr. Antonov-Ovseyenko died of a stroke, the Gulag museum announced. He is survived by his wife, Yelena Solovarova, and his son, Anton.
The Russia scholar Stephen F. Cohen, a longtime friend who smuggled "The Time of Stalin" to New York, said Mr. Antonov-Ovseyenko preferred the solitude of his books and archives to the protests favored by many other dissidents.
But he was also bold, Mr. Cohen said, often calling up known K.G.B. agents and threatening to denounce them in writing. "He was an embattled personality and fearless," Mr. Cohen said.
This article originally appeared in The New York Times.