Masaaki Morisita (森下正明光) (27 January 1913 - 25 February 1997) was a Japanese ecologist and professor emeritus of animal ecology at Kyoto University.

In addition to his work on statistical ecology, he also studied the natural history of Japanese ants.

Morisita was born in Osaka and spent his high school years in Kōchi.

He published the book Studies on Methods of Estimating Population Density, Biomass, and Productivity in Terrestrial Animals in 1977.

Like many academics from Kyoto University, Morisita had a preference for the spelling of his name in foreign language papers, writing it as "Morisita" using Kunrei-shiki romanization, rather than the English-based Hepburn romanization "Morishita".