Truth

"Quiet, child. This is what you wanted, isn't it? I will show you... the Truth!"

- Truth to Edward Elric. "Who am I? One name you might have for me is the World, or you might call me the Universe, or perhaps God, or perhaps the Truth. I am All, and I am One. So, of course, this also means that I am you. I am the truth of your despair, the inescapable price of your boastfulness. And now, I will bestow upon you the despair you deserve."

- Truth before silencing Father.

The Truth is an anti-villain from Fullmetal Alchemist. It is the supposed supreme being of the universe, and is sometimes referred to as the Universe or the World itself. Truth oversees all uses of alchemy performed, and ensures that all uses of it are following the laws and rules applicable. This includes punishing forms of alchemy that break the laws of the pseudoscience through means that it sees fit. For the act of Human Transmutation, which breaks the rule of Equivalent Exchange, Truth takes the offender to their gate and forcibly takes the things they value the most.

Truth is shown to appear differently to every individual, appearing as a blank form of themselves. As such, Truth is voiced by whatever actor is currently with them. Its voice actors include Romi Park (Japanese) and Vic Mignogna (English) when with Edward Elric, Rie Kugimiya (Japanese) and Maxey Whitehead (English) when with Alphonse Elric, and Luci Christian, who also played Wrath, for all other English appearances.

History
Truth first appears after Edward and Alphonse fail a Human Transmutation designed to resurrect their dead mother, and Edward is brought before his Gate. Truth appears, resembling a blank and white version of Edward himself. Truth taunts him, then opened the Gate to reveal vast information on the limits and laws of alchemy. Truth told Edward that, in order to repay for this knowledge and his attempt at bringing back human life, he must pay a fine. Truth then strips away Edward's leg and attaches it to itself. Edward is returned to the physical world, only to find that Alphonse's entire body and soul had been taken. In a desperate attempt, Edward drew a Blood Rune on a suit of armor and transmuted again, giving Truth his arm in exchange for his brother's soul. However, upon returning, Alphonse had no memory of the Gate or Truth.

Truth continues to appear to Edward in nightmares until he is eaten by Gluttony, whose insides are an inaccurate recreation of the Gate. He transmutes with the organic matter he finds within, but uses a piece of Envy's Philosopher's Stone as payment as opposed to more of his soul and/or body. As he is escaping, Edward stumbles across Alphonse's Gate and sees Alphonse's body, taken and used by Truth. Before he can reach the body, Edward is pulled back to his own Gate.

It is found out that Edward and Alphonse's teacher, Izumi Curtis, tried to perform Human Transmutation to bring back her stillborn child. As punishment, Truth took several of her internal organs, causing her to become sterile and have chronic haematemesis.

When Roy Mustang was forced to open the Gate, Truth was forced to take his eyesight as punishment, despite the fact that Mustang did not willingly perform Human Transmutation.

When Father gains his power, he mocks Truth and states that it is a cruel thing that only exists to make people suffer, using Edward, Alphonse, Izumi, and Mustang as examples. Edward battles Father, and Alphose decides to sacrifice his soul so that Edward can regain his arm and get an advantage. Edward transmuted Al's Blood Rune, and Truth gains Al's soul once more. Al's body and soul are reunited and Truth asks if Edward is planning a way to come back to him. Al replied positively. Back in the physical world, Edward, aided by Greed, is able to defeat Father.

Father's physical form is destroyed, and his simplified Homunculus form is brought back before Truth and the Gate. He begs Truth for mercy by trying to justify himself, but Truth mocks him, opens the Gate, and has him returned as knowledge back to the void from whence he came.

Truth then appears before Edward, asking him what he will give to return Al, body and soul, back to the physical world. Edward decides to give up his Gate, thus losing all powers of alchemy. Truth is surprised by this and asks Edward how he will live without alchemy. Edward declares that he sill has friends, and that alchemy can be given as a fair trade. Truth enthusiastically tells Edward that he has figured it out, and that the Portal to Truth was a fair trade. It then returns Al and Edward to the physical world, though Edward cannot ever perform alchemy again.

Eye of God
The Eye of God is the entity located behind the Gate, and is supposed to be knowledge itself. No mortal can ever travel to its domain, and whenever a law of alchemy is broken, it drags the offender just beyond the Gate to instill the literal truth into their minds. However, there is increased speculation and probability that the entity and Truth are one in the same, as they are both called "God" and share a connection to the Gate. When Edward sacrifices his Gate, he is cut off from the Truth and severs his ties to the being beyond. This would state that Truth and/or the entity are the source(s) of all alchemy.

Personality
Truth is cunning and merciless, but also fair and wise. It believes in the upholding of alchemy's laws and rules by any means, and any disobedience of them to result in harsh punishment. Truth always does what it believes is fair in trade, and will forcefully take from offenders. Truth holds no bias, option, or prejudice, as it sees all those who break the rules of alchemy as equal in their offenses, and thus shall receive equal punishment by losing what they value. Truth shows no favorites of its victims, and no mercy or exceptions are ever made. Despite all of this, Truth is trying to uphold the laws that bind the universe, and thus punishes any that try to perform acts that cannot happen.

Appearance
Truth is shown to appear differently to each individual, appearing as a blank version of themselves. To Edward, this appears as a white, featureless humanoid shaped like himself. This version of Truth has no form outside of the shape and a large, white mouth. Truth is surrounded by a haze of black that outlines the figure. Truth also possesses anything it has taken from a respective individual; Edward's version of Truth possesses his arm and his leg, Alphonse's version possesses his whole body, and Izumi's version possesses her lost organs.

Trivia

 * Truth made a cameo appearance in the American web cartoon RWBY, on the cover of a magazine in a Dust store.