|“||Further than anybody. And I thought I knew what that meant, though the Death Eaters did not. He was referring to his Horcruxes, Horcruxes in the plural, Harry, which I do not believe any other wizard has ever had. Yet, it fitted: Lord Voldemort has seemed to grow less human with the passing years, and the transformation he has undergone seemed to me to be only explicable if his soul was mutilated beyond the realms of what we might call usual evil.||„|
|~ Professor Albus Dumbledore regarding how far Lord Voldemort could have gone crossing MEH as he creates Horcruxes.|
The "Moral Event Horizon", or "MEH" for short, refers to an action by wrongdoer that is so vile that it usually eliminates the audience's sympathy for the villain and makes it clear that they are unrepentantly evil and will not be redeemed, unless if they themselves are offended by the actions of another villain, or admit themselves that they are beyond redemption.
Whilst popularized by TV Tropes, this term not gained its name from that site, but rather from the scientific fact that nothing can escape a black hole is referred to as the boundary of the region from which no escape is possible and is known as the event horizon, hence the name.
A villain who crosses the horizon, or enters the black hole, has no hope of escaping except under extremely rare, extraordinary circumstances. All villains who fall under Pure Evil are by definition beyond the Moral Event Horizon. However, crossing the Moral Event Horizon does not necessarily make a wrongdoer as such, it only means that they are irredeemably evil. Some villains have or almost crossed the Moral Event Horizon, or done something despicable enough to make the fans believe they did so, only to later redeem completely or partially.
A strong example of a Purely Evil villain would be either a villain who (in addition to having no or a very poor excuse for being evil) commits multiple especially heinous Moral Event Horizon-worthy deeds, or if the line in question proves to be heinous enough.
The notable consequence on the villains' reputation whom crosses MEH would led either Unspeakable Evil mere mention of their name as a taboo and believed to bring bad luck to those who utter it (or in extreme causes disease, death, or other preternatural curses) or they themselves becoming Damned Souls when they died. By definition, a character can only cross the Moral Event Horizon once; however, it is possible for a villain to have more than one event as a potential Moral Event Horizon, such as the various adaptations of the Joker of DC Comics and Teridax of BIONICLE. Other villains have more than a potential and often leave an impact on the public that they do wicked things all the time and commit Moral Event Horizon acts like a hobby, such as Lord Voldemort of the Harry Potter book series, Sir Isaac Ray Peram Westcott of the anime show Date a Live, Emperor Palpatine of the Star Wars movie franchise and Emperor Tathagata Killer of the sci-fi/fantasy animated film The Mystical Laws.
These characters are almost invariably Pure Evil.
- Moral Event Horizon on TV Tropes.