Lennart Carleson (b. 1928) is a Swedish mathematician, known as a leader in the field of hard analysis . He was a student of Arne Beurling. He is currently a professor at UCLA.

His work has included the solution of some outstanding problems, by means of combinatorial techniques . These include the corona theorem in the theory of Hardy spaces, the almost everywhere convergence of Fourier series for square-integrable functions, and work in complex dynamics.

He has been awarded the Wolf Prize in Mathematics, in 1992, amongst other honours.