Objects and artifacts that drive their wielder to evil have a recurring presence in fiction. They can allow a character to be corrupted and turn evil for a short space of time, giving the actor a chance to put a new spin on their portrayal and inviting conflict between characters that wouldn't normally have it, without the long-term consequences that would come from the character themselves turning to villainy.
As a result, these objects have shown up time and time again across all types of fiction. Television is no exception, with the threat of an artifact corrupting a side or even main character serving as a common plot device for a single episode.
10 The Thirty Pieces Of Silver Demand Vengeance (Sleepy Hollow)
A common trend in evil objects is that they don't replace the user's personality, or just arbitrarily turn them evil. They instead amplify existing motions or draw on the feelings already within a person.
In Sleepy Hollow, one of the Thirty Pieces of Silver paid to Judas Iscariot to betray Jesus of Nazareth turns up, forcing anyone who comes into possession of it to seek revenge for even the most minor of transgressions. Among other things, it causes a woman to shoot up her place of work, a man to kill his father for pressuring him into the family business, and even Benedict Arnold's betrayal.
9 The Mark Of Cain Turns Dean Into A Demon (Supernatural)
The plot of Supernatural's ninth season revolves around the Winchester brothers attempting to stop Abaddon, a Knight of Hell and nearly unstoppable demon. She's far more physically powerful than nearly any foe they had fought up until that point, and immune to all of their weaponry.
The only way to gain the power to defeat her is for Dean to absorb the Mark of Cain, the first murderer, and to wield the First Blade. Both corrupt him, but it is the Mark that leads him to seek out more and more violence. When Dean is killed, the Mark resurrects him as his worst nightmare, a demon.
8 Snake's Hair Makes Homer Murder (The Simpsons)
The Simpsons puts a comedic spin on the trope in the 'Treehouse of Horror IX' segment 'Hell Toupee.' In this segment, the criminal Snake is executed for smoking outside of the Kwik-E Mart, which is witnessed by Apu, Bart, and Moe. Following Snake's death, Homer has his hair transplanted onto his head.
The hair ends up possessing Homer with Snake's personality and forces him to murder Apu and Moe for serving as witnesses. It even forces Homer to attack his son, until Homer is able to rip it off once Bart begs for his life.
7 The Book Of Pure Evil Does Not Hide Its Intentions (Todd And The Book Of Pure Evil)
The titular object from Canadian series Todd and the Book of Pure Evil appears to people who have a desperate need, and promises to help them fulfil it. If they agree, it twists their wishes in evil ways, sometimes possessing them to ensure misery is spread.
In the show's very first episode, the Book of Pure Evil grants Todd supernaturally gifted guitar skills, but also turns him evil. At the episode's climax, Todd nearly uses his newfound powers of rock to kill his entire school, and the Book continues to warp the wishes of others at the school throughout the show.
6 The Sarcophagus Raises The Dead At A Price (Stargate SG-1)
One of the most remarkable pieces of Goa'uld technology in Stargate SG-1 is the Sarcophagus, a device that can extend the lifespan of the wielder, heal injuries, and even bring back the recently deceased from the dead.
However, it is said to steal the soul, and is credited for being the reason behind the great evil of the Goa'uld, turning those who use it selfish and callous. It even negatively affects major character Daniel Jackson when he uses it repeatedly, causing him to care about nobody other than himself.
5 The Apple Of Discord Worsens A Person (The Librarians)
In The Librarians, one of the many artifacts the characters have to deal with is the Apple of Discord. Rather than outright turn people into more evil versions of themselves, the Apple very specifically turns a person into the worst possible version of themselves.
This tends to be more harmless than other evil objects, simply making people unpleasant. One character berates museum staff, another lapses into megalomania, and a narcissist who holds it simply doesn't change, already being the worst possible version of himself. The only major threat it causes is in Cassandra Cillian, who plots to devastate Europe's power supply for fun.
4 The Coins Of Zakynthos Tend Towards Megalomania (Grimm)
In Grimm, the Coins of Zakynthos warp the mind of those in possession of them, forcing them to experience delusions of grandeur and of great power. When Sean Renard gets ahold of them, he begins to believe that he deserves mass adoration for everything he does.
On its own, this is more unpleasant than actively dangerous. However, the Coins also instill those who possess them with a homicidal urge to retain them, leading the possessor to violence against those who try to take them, or even those who they worry might attempt to.
3 The Power Of The Nightosphere Amulet Comes At A Cost (Adventure Time)
In Adventure Time, one of the many artifacts that Jake and Finn come across is the Nightosphere Amulet, an object that, if its power is used, turns the bearer into a terrifyingly powerful demon with magical powers.
However, it comes at the very explicit cost of turning a character evil, specifically changing their alignment to that of Chaotic Evil from Dungeons & Dragons, even the 'pure of heart' Finn.
2 The Blade Of Azrael Is Bad To Angels, Worse To Mortals (Lucifer)
When the Archangel Uriel seeks to kill Goddess in Lucifer, he retrieves the Blade of Azrael to do it, one-third of the greatest weapon in the universe. It is considered abhorrent by angels merely for its ability to destroy the soul of whatever it kills.
In the hands of humans, it is even worse. Aside from its soul-destroying properties, it also increases the aggression and homicidal urges of those who pick it up, turning even peaceful and harmless people into ready and willing murderers at the slightest provocation.
1 The Shroud Of Rahmon Incites Conflict In All Around It (Angel)
The focus of the Angel episode of the same name, the Shroud of Rahmon corrupts not just the one holding it, but everyone around them into aggression, mindless violence, and eventually insanity. The demons attempting to steal it eventually devolve into infighting, and even main characters like Angel, Gunn, and Kate fall prey to it.
In particular, while in the presence of the Shroud, Angel bites Kate, drinking warm human blood for the first time in decades. While it serves as part of another plan, it is an unusually aggressive move for Angel, and he clearly wishes to do so again afterwards.