Annihilator may refer to:
- A concept in ring theory, see Annihilator (ring theory)
- A type of differential operator, used in a particular method for solving differential equations, see Annihilator method
- A Canadian heavy metal band, see Annihilator (band)
- In DC Comics, as well as in the DC Animated Universe. the Annihilator was an extremely powerful magical automaton forged by the Greek god Hephaestus
- In the PC strategy game Total Annihilation, the Annihilator was an energy cannon that could destroy most enemy targets opponents in a single shot