In particle physics, antimatter is the extension of the concept of the antiparticle to matter, where antimatter is composed of antiparticles in the same way that normal matter is composed of particles.

One gram of antimatter annihilating with one gram of matter produces 180 terajoules (annihilation is defined as "total destruction" or "complete obliteration" of an object), the equivalent of 42.96 kilotons of TNT (approximately 3 times the bomb dropped on Hiroshima).

The effect of a large antimatter bomb is similar to that of a nuclear explosion of similar size. The reacting antimatter would release about half of its energy in a form immediately available to the environment, superheating the casing and components of the bomb and the surrounding air, and turning it into an ultrahot plasma which then emits Thermal Radiation in the full EM spectrum. A quantity as small as a kilogram of antimatter would release 1.8×1017 J (180 petajoules) of energy. Given that roughly half the energy will escape as non interacting neutrinos, that gives 90 petajoules of combined blast and EM radiation, or the rough equivalent of a 20 megaton thermonuclear bomb.

Characters who have the power to use antimatter:

- Anti Monitor and several others from DC Comics
- Girantina (Pokemon)
- Imperialdramon and a few other Digimon
- Ryo Takatsuki (The Jabberwock) (Project ARMS)
- Omega (Doctor Who)

Weapons which have the power to use antimatter:

- Mjolnir
- Stormbreaker