Robert Harding Whittaker (December 27, 1920 – October 20, 1980) was an American plant ecologist, active from the 1950s to the 1970s.

He was the first to propose the five kingdom taxonomic classification of the world's biota into the Animalia, Plantae, Fungi, Protista, and Monera in 1969.

[3][4] Whittaker was elected to the National Academy of Sciences in 1974, received the Ecological Society of America's Eminent Ecologist Award in 1981, and was otherwise widely recognized and honored.

[5] In 1954, he was hired as an instructor in the Department of Biology of Brooklyn College, the City University of New York.

[5] Whittaker married biochemist Clara Buehl (then a coworker at Hanford Laboratories) in 1952.