Elliott Waters Montroll (May 4, 1916, in Pittsburgh, Pennsylvania – December 3, 1983, in Chevy Chase, Maryland) was an American scientist and mathematician.

A paper published jointly with Joseph E. Mayer in 1941 Statistical mechanics of imperfect gases also examined ideas developing out of his thesis.

Montroll had an exceptionally varied career: was a Sterling Research Fellow at Yale University where his work on the Ising model of a ferromagnet led him to solve certain Markov chain problems.

Following this he was a research associate at Cornell University in 1941–42 where he began his studies of the problem of finding the frequency spectrum of elastic vibrations in crystal lattices.

[1] In 1943, Montroll was appointed as Head of the Mathematics Research Group at the Kellex Corporation in New York, working on programs associated with the Manhattan Project.