Howard Scott Gentry (1903-1993) was an American botanist recognized as the world's leading authority on the agaves.

He worked for the United States Department of Agriculture, and was a research botanist with the Desert Botanical Garden in Phoenix, Arizona after 1971. He also collected many of the specimens now at the Huntington Botanical Gardens in San Marino, California.

His 1942 study of the plants of the Río Mayo region of northwestern Mexico became a classic for the extent of its coverage of a previously little-known area.

In addition to purely botanical work, he was interested in ethnobotany, and his plant descriptions include information about their uses by indigenous peoples.

Works

• Río Mayo Plants of Sonora-Chihuahua (1942), later updated posthumously as Gentry's Rio Mayo Plants (University of Arizona Press, 1998) ISBN 0-8165-1726-6
• The Agave Family of Sonora (USDA, 1972)
• The Agaves of Baja California (California Academy of Sciences, 1978)
• Agaves of Continental North America (University of Arizona Press, 1982) ISBN 0-8165-2395-9