The Berserker powerup in Doom 3 has a lot of things in common with its classic counterpart, the berserk pack. However, the Berserker only has an effect for a limited duration and also makes the player invulnerable in singleplayer as well as the enhancement of melee attacks. It also enhances the damage far beyond what the classic powerup did, enabling the player to kill even the toughest non-boss monsters with a single punch.
The powerup resembles a fearsome looking metallic skull that appears to be wearing a marine helmet with horns, floating in midair. When the powerup is active, the player's vision is heavily blurred and distorted, combined with the constant screaming sounds. This strongly suggests the demonic origins of the Berserker.
The Berserker appears only twice in the game, being found in Communications Transfer and in Hell. In the expansion, the Berserker does not appear in singleplayer at all, being replaced by the Artifact, but appears in multiplayer.