Joseph Lehner (29 October 1912, New York City – 5 August 2013, Haverford, PA) was a mathematician at Michigan State University (1957–1963), the University of Maryland (1963–1972), and the University of Pittsburgh (1972–1980). He worked on automorphic functions and introduced Atkin–Lehner theory.
Lehner, Joseph (1964), Discontinuous groups and automorphic functions, Mathematical Surveys, VIII, Providence, R.I.: American Mathematical Society, MR 0164033 Lehner, Joseph (1966), A short course in automorphic functions, New York-Toronto, Ont.-London: Holt, Rinehart and Winston, MR 0201637 Lehner, Joseph (1969), Lectures on modular forms, Applied Mathematics Series, 61, National Bureau of Standards, MR 0264070 Atkin, A. O. L.; Lehner, J. (1970), "Hecke operators on Γ0 (m)", Mathematische Annalen, 185: 134–160, ISSN 0025-5831, MR 0268123, doi:10.1007/BF01359701 