Nicomedes may refer to:
- Nicomedes (mathematician), ancient Greek mathematician who discovered the conchoid
- Nicomedes of Sparta, regent during the youth of King Pleistoanax, commanded the Spartan army at the Battle of Tanagra (457 BC)
- Saint Nicomedes, Martyr of unknown era, whose feast is observed 15 September
Four kings of Bithynia in Anatolia, 3rd–1st century BC:
- Nicomedes I of Bithynia, ruled 278–255 BC
- Nicomedes II of Bithynia, 149–127 BC
- Nicomedes III of Bithynia, 127–94 BC
- Nicomedes IV of Bithynia, 94–74 BC