Deimos, a Greek word for dread, may refer to:
- Deimos (deity), one of the sons of Ares and Aphrodite in Greek mythology
- Deimos (moon), the smaller and outermost of Mars' two natural satellites
- Elecnor Deimos, a Spanish aerospace company
- Deimos-1, an artificial Earth observation satellite
- Deimos-2, an artificial Earth observation satellite
- Deimos (launch platform), a floating launch platform currently in refit by SpaceX
- Deimos (comics), villain for the Warlord comic series
- DEIMOS, an early message passing OS for the Cray-1, replaced by the Cray Time Sharing System
- Deimos (Doctor Who audio), an audio drama
- Deimos, the brother of Kratos in the God of War series
- USS Deimos (AK-78), a ship in the US Navy in World War II
- Deimos, the identity of an antagonistic character from the 2018 video game Assassin's Creed Odyssey