Thomas Campbell EytonJP, DL (10 September 1809 – 25 October 1880) was an English naturalist whose fields were cattle, fishes and birds. He was a friend and correspondent of Charles Darwin though he opposed his theories.
Eyton published History of the Rarer British Birds (1836), A Monograph on the Anatidae, Or Duck Tribe (1838), A History of Oyster and Oyster Fisheries (1858) and Osteologia Avium (1871–78). He established in about 1842 the "Herd Book of Hereford Cattle", which he edited until 1860
Eyton was married in 1835 to Eizabeth Frances Slaney, the eldest daughter and co-heiress of Robert Aglionby Slaney MP. She pre-deceased him by ten years.