John Treadwell Nichols (June 11, 1883 – November 10, 1958) was an American ichthyologist and ornithologist.

[1] In 1906 he studied vertebrate zoology at Harvard College, where he graduated with a Bachelor of Arts (AB).

[2] In 1916 he described the long lost Bermuda petrel together with Louis Leon Arthur Mowbray who first sighted this bird within a flock of other petrels in 1906 on Castle Island, Bermuda 45 years before it was officially rediscovered by Mowbray's son Louis.

He also worked with a team of scientists from the American Museum of Natural History during the Jersey Shore shark attacks of 1916.

Nichols wrote 1,000 articles and several books (mostly about fish but also about birds), and he made many expeditions around the world.