Alwyn Howard Gentry (January 6, 1945 – August 3, 1993) was an American botanist and plant collector, who made major contributions to the understanding of the vegetation of tropical forests.

His method, allied to his encyclopedic knowledge of tropical plants, allowed him to sample a site in a matter of days, and over the course of his career he amassed data from over 200 such transects worldwide.

[3] This ability that led to the publication of his Field Guide to the Families and Genera of Woody Plants of Northwest South America,[4] completed just months before his death.

[3] On August 3, 1993, Gentry was on a Rapid Assessment Program mission in western Ecuador, when the light aircraft in which he was traveling crashed into a mountain ridge near Guayaquil.

[6] Four people—the pilot, Gentry, American ornithologist Theodore A. Parker III, and Ecuadorian ecologist Eduardo Aspiazu—died in the crash; three other researchers including biologist Alfredo Luna Narváez survived.