The epicenter or epicentre (ancient Greek: επίκεντρον) is the point on the Earth's surface that is directly above or below the center of a localized explosive event or point of seismic energy release.

The epicenter is directly above the hypocenter, the point at depth where an earthquake originates. The hypocenter is the actual location of the earthquake energy release inside the earth. Seismic waves propagate spherically out from the hypocenter. Seismic shadowing occurs on the opposite side of the Earth from the earthquake epicenter because the liquid outer core absorbs the transverse or shear waves (S-waves), and refracts the longitudinal or compressional (P-waves).

An epicenter is also located directly below the point of an air or surface detonation of a nuclear weapon and it is strictly above the point of the underground detonation.

The terminology is also applicable to other catastrophic events, such as an impact or explosion of a meteorite or comet.