Haakon Chevalier

American translator, writer and academic (1901–1985)

Haakon Maurice Chevalier (September 10, 1901 – July 4, 1985) was an American writer, translator, and professor of French literature at the University of California, Berkeley best known for his friendship with physicist J. Robert Oppenheimer, whom he met at Berkeley, California in 1937. Oppenheimer's relationship with Chevalier, and Chevalier's relationship with a possible recruiter for Soviet intelligence, figured prominently in a 1954 hearing of the U. S. Atomic Energy Commission on Oppenheimer's security clearance. At that hearing, Oppenheimer's security clearance was revoked.

Chevalier was born September 10, 1901, in Lakewood Township, New Jersey to Therese Chevalier (née Roggen) and Emile, respectively of Norwegian and French descent. When he was in his twenties Chevalier felt attracted by the romantic aspects of seafaring. He embarked as a deckhand on one of the last commercial sailing ships, the four masted US schooner Rosamond, for a voyage to the southern ocean and Cape Town. Chevalier wrote a vivid and nostalgic testimony of this very end of the age of sail in his book The Last Voyage of the Schooner Rosamond.

In 1945, Chevalier served as a translator for the Nuremberg Trials. He translated many works by Salvador Dalí, André Malraux, Vladimir Pozner, Louis Aragon, Frantz Fanon and Victor Vasarely into English.

Chevalier met Oppenheimer in 1937 at Berkeley while he was an associate professor of Romance languages. Together, Chevalier and Oppenheimer would found the Berkeley branch of a teachers' union, which sponsored benefits for leftist causes. Chevalier informed Oppenheimer in 1942 of a discussion he had with George C. Eltenton which disturbed him considerably and which he thought Oppenheimer ought to know about. It was regarding Soviet attempts through Eltenton to penetrate the Manhattan Project. That short conversation, Oppenheimer's belated reporting of it, and attempts to obscure the identity of Chevalier, would later become one of the key issues in Oppenheimer's 1954 security hearing in front of the Atomic Energy Commission, which resulted in the revocation of his security clearance. Chevalier was interviewed in The Day After Trinity (1981), an Oscar nominated documentary about Oppenheimer and the atomic bomb. He was played by Jefferson Hall in Christopher Nolan's 2023 film Oppenheimer.

Chevalier had four children from three marriages. From 1922 to 1931 he was married to Ruth Bosley, then to Barbara Lansburgh from 1931 to 1950, and finally to Carol Lansburgh in 1952.

After the House Subcommittee on Un American Activities hearing, Chevalier lost his job at Berkeley in 1950. Unable to find another professorship in the United States, he moved to France, where he continued to work as a translator. Chevalier returned to the United States briefly in July 1965, to attend his daughter's wedding in San Francisco.

Jefferson Hall portrays Chevalier in the 2023 epic biopic film Oppenheimer.