Abram Samoilovitch Besicovitch (Besikovitch) (Абрам Самойлович Безикович) (24 January 1891 - 2 November 1970) was a Russian mathematician, who worked mainly in England. He was born in Berdyansk on the Sea of Azov (now in the Ukraine) in a family of Karaite Jews.

He studied under A. A. Markov at the University of St. Petersburg, graduating in 1912. He then began research in probability theory. He converted to Eastern Orthodoxy, joining the Russian Orthodox Church, on marrying in 1916. He was appointed professor at the University of Perm in 1917, and was caught up in the Civil War over the next two years. In 1920 he took a position in Petrograd University.

In 1924 he went to Copenhagen and Harald Bohr, on a Rockefeller Fellowship , where he worked on almost periodic functions, which now bear his name. After a visit to G.H. Hardy in Oxford, he had appointments at Liverpool University in 1926, and the University of Cambridge in 1927.

He worked mainly on combinatorial methods and questions in real analysis, such as the Kakeya needle problem and the Hausdorff-Besicovitch dimension. These two particular areas have proved increasingly important as the years have gone by.

He was a major influence on the economist Piero Sraffa, after 1940, when they were both Fellows of Trinity College, and on Dennis Lindley , one of the founders of the Bayesian movement in the United Kingdom.

He was J.E. Littlewood's successor in 1950 in the Rouse Ball chair at Cambridge, retiring in 1958. He died in Cambridge.