In Greek mythology, Mermerus (Ancient Greek: Μέρμερος, romanized: Mérmeros, lit. 'anxious', 'mischievous' or 'baneful') may refer to the following personages:
Mermerus, a Centaur.
Mermerus, son of Jason and Medea.
Mermerus, a son of Pheres, and grandson of Jason and Medea. He was the father of Ilus who played host to Odysseus and skilled in the art of preparing poison.
Mermerus, a Trojan who was killed in a battle during the Trojan War. His armor was then stripped off his body by Antilochus.