Otto Stapf was an Austrian botanist.
Stapf trained in Vienna, and moved to the Royal Botanic Gardens, Kew in 1890. He was the keeper of the herbarium from 1909-1920. In 1927, he was given the Linnean Medal.
Stapf wrote about the Graminae in William Turner Thiselton Dyer's edition of Flora capensis.
When citing a botanical name, he is abbreviated as Stapf.