Titan Quest is an action role playing hack and slash video game developed by Iron Lore Entertainment. It was released worldwide by THQ on June 26, 2006. The game was released on Steam, along with the expansion Titan Quest: Immortal Throne, on July 17, 2007. The game is also available via Impulse, GamersGate, GameTap, Direct2Drive and OnLive. In 2013, the IP for Titan Quest, along with most of THQ's other games was purchased by Nordic Games.

Titan Quest is based on the end of communication between the gods and humanity. The main character (whose name and sex can be chosen by the player) begins the quest on a dirt road near a small village named Helos. The world has been overrun by beasts and creatures (drawn largely from mythology) that are terrorizing the countryside wrecking harvests, burning temples, invading villages and cemeteries, besieging cities etc. After being sent on a mission to Delphi by the Spartan general Leonidas, the story revolves around the fictional order of Prometheus and their efforts to restore balance to the world. The hero finds centaurs, harpies, automatons, spiders and scorpions, yetis, undead soldiers and other such monsters derived from myth, relentlessly guarding the way and trying to prevent him from reaching the next village or town. The hero must occasionally face stronger 'miniboss' monsters, usually as part of a side quest. Bosses also appear at intervals generally guarding a main quest item, transportation device, quest NPC, etc. The player faces a boss enemy (called telkines) at the end of each 'act' (Greece, Egypt and The Orient) and faces a final boss enemy at Mount Olympus, the Titan Typhon.