Each character belongs to one of the two nations of the game: El Morad (humans) or Karus (orcs, although the game calls them "Tuareks").
Knight Online has four character classes available for both nations: Warrior, Rogue, Mage, and Priest. Each class has a basic skill set, three main skill sets (after 1st job change), and one master skill set (after 2nd job change).
Warrior Melee fighter. High amount of health. Good defense (Main tanker in game) Attack, Defense, Berserker Berserker Hero(Karus), Blade Master(El Morad)
Rogue Variable. May use ranged attacks or melee. Also learns healing, curing, invisibility, and speed skills. Archer, Assassin, Explorer Kasar Hood(El Morad),Shadow Vain(Karus)
Mage Characters with ranged magical attacks, able to inflict continuous and area of effect (AoE) damage, slow down, or stun enemies. Can teleport party members. Flame, Glacier, Lightning Elemental Lord (Karus), Arch Mage (El Morad)
Priest Main support character. Used to increase statistics such as HP, heal party members, and decrease statistics of enemies. They have non-support attacker builds too. Healing, Aura, Holy Spirit Shadow Knight (Karus), Paladin (El Morad)