Pavel Samuilovich Urysohn, Pavel Uryson (Па́вел Самуи́лович Урысо́н) (February 3, 1898, Odessa – August 17, 1924, Batz-sur-Mer) was a Jewish mathematician who is best known for his contributions in the theory of dimension, and for developing Urysohn's Metrization Theorem and Urysohn's Lemma, both of which are fundamental results in topology. His name is also commemorated in the term Menger-Urysohn dimension and in the term Urysohn integral equation. The modern definition of compactness was given by him and Pavel Alexandrov in 1923.
Urysohn studied at Moscow University from 1915 to 1921. His advisor was Nikolai Luzin. He then became an assistant professor there. He drowned in 1924 while swimming off the coast of Brittany, France, near Batz-sur-Mer, and is buried there.
Urysohn's sister, Lina Neiman wrote a memoir about his life and childhood. Not being a mathematician, she included in the book memorial articles about his mathematical works by Pavel Alexandrov, Vadim Efremovich, Andrei Kolmogorov, Lazar Lyusternik, and Mark Krasnosel'skii.