The Living Tribunal's true function - the task for which it was created - is to protect the worlds without end, to whom Earth is but a speck of dust. He safe-guards the multiverse from mystical imbalance and transcends the realms of death and eternity, order and chaos and all opposing realities. All the dimensions, each nebulous netherworld which exists either in time or in space - either as matter, or as fathomless void - such were given over into the eternal, deathless keeping of the Living Tribunal, by the Supreme Being of the Marvel Multiverse - the entity called by cosmic entities "the One-Above-All".
His half cloaked face represents vengeance, his cloaked face represents necessity and his full face represents equity. Everywhere in existence has the presence of the trinity. He uses all three faces to look upon the world and judge. He judges these dualities and must know their true nature. He could have a fourth face, which represents nothing. Mortal mutterings such as good and evil - right and wrong - have no meaning to such as the Living Tribunal.
The Living Tribunal was created jointly by Stan Lee, Marie Severin and Herb Trimpe first appearing in the Strange Tales title in June of 1967
Major Story Arcs
The Infinity Gauntlet is a gauntlet that contains the six Infinity Gems. Whoever possesses the Infinity Gauntlet gains virtual omnipotence, making the Infinity Gauntlet one of the most powerful artifacts of the Marvel Universe. The Living Tribunal has demonstrated power beyond that of the gauntlet on several occasions.
When Thanos got the Infinity Gauntlet, giving him all the powers of Power, Reality, Space, Time, the Mind, and the Soul, the Living Tribunal was the only one who was not affected by the will of the gauntlet. He was asked to empty the powers of the gauntlet because of the doom that Thanos might bring with it, and he refused to. This is to say that while the Living Tribunal had the power to he chose not to. After Thanos lost the gauntlet to Nebula, who lost it to Adam Warlock, the Living Tribunal was the only one who could stand up to the power wielded by the gauntlet.
Adam Warlock lost his temper during a trial, while Eternity was trying to prove his case that Adam Warlock was unfit to keep the Infinity Gauntlet in his possession to the Living Tribunal. When Adam Warlock lost his temper, his temper exploded, similar to a bomb going off with everyone being blown away from Adam Warlock. Then, in an instant, the Living Tribunal said, "Let order be restored to this hearing." and everything was back in order, again proving power over (or mastery of without contact with) the Infinity Gems. The Living Tribunal eventually decreed that the combined power of the Infinity Gems could no longer be summoned by one person bearing the Infinity Gauntlet again.
Thus, the Infinity Watch was formed and the infinity gems were separated.
When Thanos and Adam Warlock teamed up to defeat the Magus, Thanos suggested Warlock use the Infinity Gauntlet. But to their surprise, it would not work. The Living Tribunal had taken away the power of the gems when together. Galactus went to have a hearing with the Tribunal to restore their power. The Tribunal claimed the decision should be made by Eternity, who was in a catatonic state. Galactus was able to get Eternity to speak with the use of Gamora and the power was restored. But they unknowingly restored the power when Magus had obtained the gauntlet.
After Magus' defeat, the power of the gems together was once again removed, never under any circumstance to be reinstated.
Powers and Abilities
The Living Tribunal possesses limitless power, able to erase whole realities from existence. As such, the Living Tribunal is omnipotent, omniscient, and omnipresent.
The Living Tribunal is the second most powerful being in the Marvel Universe, only surpassed by The One-Above-All (not the Celestial). For reference see the All-New Official Handbook of the Marvel Universe A-Z #6.
The Living Tribunal is omniversal and exists in every reality at once.