The name Ismarus may refer to:

• Ismarus (Thrace), a city of the Cicones, on the Aegean coast of Thrace, mentioned in the Odyssey
• A mountain of the same name, "Ismaros"; see Ismarus (Thrace)
• Ismarus (wasp), a genus of wasps

• Ismarus, defender of Thebes who killed Hippomedon
• Ismarus (Immaradus), son of Eumolpus and son-in-law of the Thracian king Tegyrios