Otto Albin Frostman (3 January 1907 – 29 December 1977) was a Swedish mathematician, known for his work in potential theory and complex analysis.

Frostman earned his Ph.D. in 1935 at Lund University under the Hungarian-born mathematician Marcel Riesz, the younger brother of Frigyes Riesz. In potential theory, Frostman's lemma is named after him.^[1] He supervised the 1971 Stockholm University Ph.D. thesis of Bernt Lindström, which initiated the "Stockholm School" of topological combinatorics (combining simplicial homology and enumerative combinatorics).