Eo or EO may refer to:
The Eocene ( ) Epoch, lasting from 56 to 33.9 million years ago, is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era.
Eobard Thawne, otherwise known as Professor Zoom and the Reverse-Flash, is a fictional supervillain appearing in comic books published by DC Comics.
Eoin Joseph Gerard Morgan (born 10 September 1986) is an Irish-born cricketer who captains the England cricket team in limited overs cricket.
EOKA (; Greek: ΕΟΚΑ), acronym for Ethniki Organosis Kyprion Agoniston, was a Greek Cypriot nationalist guerrilla organisation that fought a campaign for the end of British rule in Cyprus, for the island's self-determination and for eventual union with Greece.
Eosinophils, sometimes called eosinophiles or, less commonly, acidophils, are a variety of white blood cells and one of the immune system components responsible for combating multicellular parasites and certain infections in vertebrates.
Eosinophilic granulomatosis with polyangiitis (EGPA), also known as allergic granulomatosis, is an extremely rare autoimmune condition that causes inflammation of small and medium-sized blood vessels (vasculitis) in persons with a history of airway allergic hypersensitivity (atopy).
Eoin Colfer (; born 14 May 1965) is an Irish author of children's books. He worked as a primary school teacher before he became a full-time writer.
Eolambia (meaning "dawn lambeosaurine") is a genus of herbivorous hadrosauroid dinosaur from the early Late Cretaceous of the USA.