Titan Quest assigns your character a class as soon as you choose a skill mastery. If you decide to pursue a second mastery later in the game, your class will change to reflect your diverse talents. What follows is a list of all thirty-six of the game's original class combinations, as well as the nine additional classes added in the Titan Quest: Immortal Throne expansion pack:

Dream Mastery [Immortal Throne Only]

* Single Profession: Seer
* + Storm Mastery: Prophet
* + Earth Mastery: Evoker
* + Warfare Mastery: Harbinger
* + Spirit Mastery: Diviner
* + Defense Mastery: Templar
* + Nature Mastery: Ritualist
* + Hunting Mastery: Haruspex
* + Rogue Mastery: Dreamkiller

Storm Mastery

* Single Profession: Stormcaller
* + Earth Mastery: Elementalist
* + Warfare Mastery: Thane
* + Spirit Mastery: Oracle
* + Defense Mastery: Paladin
* + Nature Mastery: Druid
* + Hunting Mastery: Sage
* + Rogue Mastery: Sorcerer

Earth Mastery

* Single Profession: Pyromancer
* + Warfare Mastery: Battlemage
* + Spirit Mastery: Conjurer
* + Defense Mastery: Juggernaut
* + Nature Mastery: Summoner
* + Hunting Mastery: Avenger
* + Rogue Mastery: Magician

Warfare Mastery

* Single Profession: Warrior
* + Spirit Mastery: Spellbreaker
* + Defense Mastery: Conqueror
* + Nature Mastery: Champion
* + Hunting Mastery: Slayer
* + Rogue Mastery: Assassin

Spirit Mastery

* Single Profession: Theurgist
* + Defense Mastery: Spellbinder
* + Nature Mastery: Soothsayer
* + Hunting Mastery: Bone Charmer
* + Rogue Mastery: Warlock

Defense Mastery

* Single Profession: Defender
* + Nature Mastery: Guardian
* + Hunting Mastery: Warden
* + Rogue Mastery: Corsair

Nature Mastery

* Single Profession: Wanderer
* + Hunting Mastery: Ranger
* + Rogue Mastery: Illusionist

Hunting Mastery

* Single Profession: Hunter
* + Rogue Mastery: Brigand

Rogue Mastery

* Single Profession: Rogue