Carl Wilhelm Oseen (1879, Lund – 1944, Uppsala) was a theoretical physicist in Uppsala and Director of the Nobel Institute for Theoretical Physics in Stockholm.
Oseen formulated the fundamentals of the elasticity theory of liquid crystals (Oseen elasticity theory), as well as the Oseen equations for viscous fluid flow at small Reynolds numbers. He gave his name to the Oseen tensor and, with Horace Lamb, to the Lamb–Oseen vortex.
Oseen was a member of the Royal Swedish Academy of Sciences from 1921, and a member of the Academy's Nobel Prize committee for physics from 1922. It was Oseen who nominated Albert Einstein for the Nobel Prize in 1921, for his work on the photoelectric effect. (As a full professor of a Swedish university, Oseen had the right to nominate Nobel Prize winners.)