In Tower of God, Grace Luslec Mircea is this to 25th Baam, to the point he adopts his name and become Jyu Viole Grace (Jyu Viole, adopted by Grace). In a way, the Tower itself, a Genius Loci, corrupts its inhabitants with the promise of having everything you wish for at the top.
Tobi/Obito Uchiha, who in turn appears to have been corrupted by Madara Uchiha
Orochimaru when he was still alive was one of these as well.
Danzo also acts as an indirect example given all the people who he has caused to make a Face-Heel Turn through his actions. All of these combined examples add up to a Gambit Pileup.
It is implied that Zabuza had a similar effect on Haku, though Haku never saw him as anything other than a loving master. More like, they met each other halfway. Zabusa taught Haku how to be harder and more ruthless, but Zabuza also learned to care about someone other than himself.
In the 2003 anime version of Fullmetal Alchemist, Lust's job is to be The Corrupter who tempts desperate alchemists into seeking the forbidden knowledge of how to make Philosopher's Stones. Envy also ends up creating Wrath by tempting the nascent homunculus with incomplete Philosopher's Stones.
Pasder and the Zonderians in GaoGaiGar, and the Primevals later on.
Naraku from InuYasha frequently tries to corrupt the hearts of the heroes; sometimes this is for a practical purpose (usually corrupting the Shikon Jewel), while sometimes it's just for the sake of evil. At one point, he tries to force Kagome to choose between killing the priestess he has mind-controlled (which would allegedly both condemn the priestess to hell and corrupt Kagome's heart for killing her knowing that) or being killed by her; at another, he tries to get Sango to kill an innocent little girl in order to kill him, which is also the only way to save her love interest's life (only Naraku wouldn't have died anyway because she was only talking to an illusion of himself).
Despite being the Big Bad, Dakki of Houshin Engi counts as this. One of her Paope gives off a sent that eventually drives men to her side and makes them devoted slaves. Mix in her own skills at manipulation with just her looks and words and you have a nasty combo to deal with. Just look at the Emperor. He starts off normal and many chapters in, gets turned into a human paope weapon that is barely aware of who he originally was. And she's been doing this for hundreds of years as well.
Soul Eater has Asura and his Clowns as well as Medusa for Crona.
LightYagami of Death Note plays this role for the (albeit less-than-heroic) Misa, Takada, and Mikami, turning each of them in turn from moderately unpleasant people with mild psychological problems to unrepentant mass murderers. Then, of course, there's his cult and the unnamed masses he screwed up there...
Light also inadvertently causes his father to make a deal with Ryuk that results in his death, bringing the most innocent character in the series into the mess and nearly making him a murderer too.
Darkseid, being the God of Evil of the DC Universe, has played this role from time to time. The one he bragged about to Eclipso? He once visited New Genesis long before he took on the mantle of Darkseid and saw a beautiful young boy, pure and innocent. With little more than words and the death of a pet bird, Darkseid twisted the youth and gave him a new name — Desaad.
In All Fall Down, Phylum becomes this to Pronto, thanks to a booby-trapped voice-box that gives poisonous advice.
In Hellblazer, Nergal attempted to corrupt a young John Constantine by disguising himself as a boy and offering him a cigarette. John took the cigarette and Nergal privately gloated that he had started the boy down a path of corruption. Then he noticed that John had managed to steal the entire pack from him when he wasn't looking. The two eventually become archenemies.
Grudge Song, the fourth of the Female Prisoner Scorpion films, features a desperate attempt by the protagonist to do this to a calm, earnest Buddhist inmate in order to cause enough havoc to escape from Japan's equivalent of death row.
In Ghost Ship, it's Ferriman's job to bring out the absolute worst in people, because if they commit enough sins they'll effectively damn their souls, which he can then harvest and take to Hell. He pressures a segment of the crew on the Graza into starting a complete orgy of violent murder of everyone else on board so they can get their hands on all the gold he brought with him. He tries the same routine on the present day salvage crews, but it's only Epps who takes a definite stand against his material offers at the end.
The Un-man from Perelandra, which is fitting, since he's Satan possessing a human, in a sci-fi setting.
Sang-drax from The Death Gate Cycle, who is evil incarnate (or rather, a piece of it) and feeds off of hatred, fear, and suffering — convincing mortals to do evil is his equivalent of popping a frozen dinner into a microwave.
Sauron — not so much in The Lord of the Rings, but definitely in the Downfall of Númenor chapter in The Silmarillion — stripped of all other resources, his last resort is to corrupt the entire Númenórean Empire and then sit back and watch their civilization spectacularly implode (unfortunately on top of him). He also corrupted the nine mortal kings who would later become the Nazgûl.
Gríma Wormtongue corrupted King Théoden. Who was in turn corrupted by Saruman who was corrupted (somewhat indirectly) by Sauron who was corrupted by Melkor. Suffice it to say, Tolkien was fond of this trope.
Randall Flagg in The Stand, who is very much a Devil-figure in the novel and onemany of Stephen King's most diabolical villains.
I, Lucifer a novel written from the devil's perspective details his various efforts to corrupt mortal souls.
Ruin from Mistborn isn't exactly encouraging people to be evil (he considers himself Above Good and Evil), but he does work to make them more destructive, which usually amounts to the same thing. Even the heroine was one of his pawns, at least for a while and without knowing it.
First Mate Cox in Nation. He makes other people like himself.
The Big Bad himself, Kullervo, from Companions Quartet has this kind of effect on others having been able to convert the Seagullls, Cassandra Lang, and the Chimera amongst others.
Harry Potter: Lord Voldemort recruited Quirrell this way, and presumably some other followers as well.
Lashiel's shadow fills this role, although Harry corrupts her, for lack of a better term, more than she does him, and in the end she pulls off a Heroic Sacrifice for him.
Cold Days reveals that the Man Behind the Man for most of the series is the Outsider saboteur, Nemesis.
In Lucifer's Hammer, Sargent Hooker and his cannibal army qualify as this. People who they capture are forced to choose between helping to kill and eat other captives, or be killed and eaten themselves. Once they've done this, most don't ever feel they can go back, so they survive by committing themselves to their new comrades. (An interesting example, because we get to see how the army becomes corrupted, then becomes the The Corrupter in order to gain new recruits.)
Tales of Kolmar: Berys managed to become Archchancellor of the College of Mages through demon-summoning, and regularly when seeing students and established healers frustrated by their limits he would offer them greater power in exchange for a lock of hair and the promise of aid when he needed it. He never tells them that said aid takes the form of sudden Demonic Possession and their magic feeding his, whenever he wants it.
Wyrm in The Book of the Dun Cow uses his Dream Weaver powers to persuade the old rooster Senex to father a son, although Senex is infertile, and makes the rooster desperate and dangerously obsessive. This son turns out to be the monstrous Cockatrice, who eventually murders Senex when he realizes that Wyrm tricked him. Senex's corruption allows Wyrm to begin freeing himself from his prison beneath the earth.
Humorously subverted with Crowley from Good Omens: he was the literal snake in the Garden of Eden and as a demon, corrupting hapless mortals is sort of his job description. He just goes about it in a very half-assed sort of way.
In the third book in the Wayside School series, while the teacher is pregnant, there is a substitute teacher who fulfills this role, turning all the students against each other and creating a very tense and hate-filled classroom.
In the third season of Ashes to Ashes, this is the whole motivation of Jim Keats. He wants to see Gene Hunt brought down and, resenting him for bringing good police officers under his sway, plans to turn the others against Gene. It seems like hemay have a point... then he grows into more of a Shadow Archetype of Gene Hunt, just as brutal but considerably more evil, and he becomes an almost Satanic figure. Then he becomes an actual Satanic figure, as it's revealed the whole reason for his corrupting of the others was so that he could lure them down to Hell. It's that kind of show.
Méléagant in Kaamelott (seasons 4, 5 and 6). Who or what he is stays unclear, but it is hinted he's incredibly ancient. With a mix of guile and carefully-used magic powers, he works at corrupting Lancelot even further than he already was, and push a depressive King Arthur toward suicide.
Mr. Morden on Babylon 5, who is introduced by going around the station asking the ambassadors "What do you want?". His job under the Shadows is to find pliable people that he can tempt into a Deal with the Devil by making them accept Shadow aid.
Darkseid and his minions Godfrey, Granny Goodness, and especiallyDesaad fullfill this role in the tenth season, turning the entire world against the JLA while strengthening their own power in the process.
Earth-2 Lionel did this to Lex, Tess, and Clark in his home universe, and tries it on Alexander when he makes his way to Earth-1.
In Season 4 of Supernatural, Ruby is revealed to be one of these. Over the season she drives Sam away from his friends, gets him addicted to demon blood and tricks him into releasing Lucifer from Hell.
The Man In Black from LOST. Not only is his smoke form a literal corruption of the Light in the Island's center, his modus operandi is to corrupt people with nightmares and apparitions, or sometimes even infect them, so he can use them as pawns to defeat Jacob.
Great Professor Bias of Choujuu Sentai Liveman sends tests to three students of Academia in the beginning, corrupting them and causing them to work for him. It turns out one of them, Goh, was corrupted by the other two and was simply let in out of pity. As such, he was ultimately saved, though the others were not.
Morgause from Merlin. Her first appearance is her attempting to get Arthur to kill Uther by telling him the truth about his conception. When that fails she whisks away Morgana for a year and has corrupted her completely when they return in season 3.
In Breaking Bad, Walter White is this both in a Downplayed intentional fashion and in an unintentional fashion. While Jesse was already in the meth business, Walt coerces and manipulates him into doing things that he would never have considered doing beforehand. Unintentionally, Walt's influence has a similar effect on everyone around him. One of the writers noted, "Walt has corrupted everyone."
The Serpent from Genesis, often identified with Satan.
The demon Mara from Buddhist mythology, who led Buddha into temptation to prevent him achieving enlightenment.
This was the entire character of Sean O'Haire's last WWE gimmick — he'd pop up to try and convince folks backstage to turn heel, in between vignettes urging ordinary people to do things like cheat on their wives simply for kicks.
This is the current character for Kane, as he's attempting to get John Cena to "embrace the hate", and presumably, turn heel.
Shedim from In Nomineare this trope; an alternate name for this particular type of demon is "Corruptors". They accomplish their corruption by Demonic Possession and driving their hosts to do things of escalating levels of evil every day, and the host thinks it was their idea in the first place.
Arguably Cassius in Julius Caesar who persuades Brutus to join the conspiracy to kill Caesar by poisoning his mind and telling him that Caesar wants to make himself a dicator. However, there is debate other whether Cassius himself actually believes what he tells Brutus.
Alexander from Amnesia: The Dark Descent fills this role quite well, especially with respect to Daniel. Taking advantage of Daniel's growing paranoia, he transforms him from a naive young man to an Ax-Crazytorturer.
Then again, one could argue that both men had already been corrupted by the Shadow.
Mephiles in Sonic 2006 fills this role, or tries to. He tries to tempt Shadow into turning evil again to "help Mephiles" in a desire for revenge, when all Mephiles actually wants to do is destroy everything. He also manipulates Silver into getting him to kill Sonic, which sticks for most of the game until Shadow convinces him of better. Luckily, it turns out Shadow is the only character with a clue. At the end, Mephiles takes matters into his own hands, and kills Sonic.
If you're playing Light-Sided, Kreia can definitely be this, viciously berating selfless actions, inflicting Mind Rape on your companions, and encouraging you to "use" and "discard" everyone like tools to advance yourself.
Atris repeatedly accuses the Exile of being this to the Handmaiden, after she decided to stowaway on the Ebon Hawk to join their quest, then later broke their oath by asking the Exile to teach her the ways of the Jedi.
"Master User" J. D. Thorne in TRON 2.0 was a User sent into Cyberspace without the necessary protocols to keep him stable, turning him into a living computer virus that seeks out Programs and twists them into Z-lots.
Molag Bal the Daedric Prince of Domination. He's even called The Corrupter in-universe.
Most of the overtly evil Daedric Princes dabble in this role in one way or another, relishing every chance to turn a mortal (particularly a Hero) to their way of thinking.
Xana from Dark Messiah spends the entire game trying to convince Sareth to accept his demonic heritage, all the while making pretty blatant come-ons and innuendo (she is a succubus after all). She also tries to convince him to not free the Demon Sovereign, and instead claim the Skull's power for himself, with her at his side.
Skelter Helter and Pizza Batt Jr. try to be this towards Travis in No More Heroes 2: Desperate Struggle, making him feel the pain he made them feel and become a monster just like them. They fail at killing the remaining friends he has, however, and also sort of forgot that Travis was already pretty corrupt to begin with.
Shin Megami Tensei has the ultimate example in Lucifer. He may not be evil, but that does not mean he's selfless or entirely benevolent. In fact, it's hinted by Word of God that Lucifer's true role is the tester of the human spirit, the entity meant to embody this for Humanity as a whole, offering, taking away and generally gambling with power as only gods can.
The IFCC from The Order of the Stick, who may have a behind-the-scenes Evil Plan going on, but are also just as interested in claiming souls as any other fiends. Sabine states that she'd seen them take down mortals way more righteous than True Neutral Vaarsuvius.
The Nostalgia Critic has been established in-universe and out as a horrible influence on people. Problem is, he doesn't know he's doing it and he's the one who usually ends up getting killed, raped or otherwise hurt in some way.
Tattletale is this to Taylor, offering her friendship without reservation and a place in her supervillain gang, which given Taylor's status as a bullied fifteen-year-old almost immediately earns her affection. This example is notable in that Tattletale genuinely does want what's best for Taylor, and thinks that she can get a sense of fulfillment and empowerment with the Undersiders that she won't get if she just keeps going to school and being bullied.
Later, Taylor herself gains this reputation after she convinces both Parian and Flechette to defect to the Undersiders.
Jack Slash excels at this, but his motives aren't nearly as benign. He even talks Scion into pulling a Face-Heel Turn and deciding to wipe out humanity.
Slade from Teen Titans, especially in Seasons One and Two.
Nerissa from W.I.T.C.H. has elements of this, though she's unusual in that she's a Well-Intentioned Extremist — it's just that she's also a big-time control freak and finds people's moral flaws to be an easily-exploitable weakness she can use to control them.
In Avatar: The Last Airbender , Azula fits this. While she doesn't bring down someone who was good, she did corrupt her brother Zuko right before he could complete his Heel-Face Turn at the end of Season 2. Despite their uncle's protests he joined her. Though he did eventually make up for it with a real Heel-Face Turn in Season 3.
Azula also manages to turn the Dai-Li against the Earth Kingdom, understanding they follow who looks most powerful.
The second season of The Legend of Korra has Unalaq, a dark priest who can turn normally good or neutral spirits into Dark Spirits.
From the 2010 French Animated Adaptation of The Little Prince, the Snake is this trope in its purest form. His modus operandi is to compel the most important person on every planet to indulge into their whims, with always disastrous results for their world. Naturally, he attempts it with the title hero too, trying to convince him to return to Asteroid B612 and leave the Snake free to corrupt people.
South Park: Cartman is exceptionally adept at pulling along otherwise decent, if not pottymouthed kids into his horrible schemes. Usually happens to Butters and Kyle.
"Crack Baby Athletic Association" has Cartman corrupt the normally morally uptight Kyle to the point that Stan calls Kyle on sounding just like Cartman.
Chase Young spends almost the entire second season working to corrupt Omi and convince him to join the forces of evil.
Third season introduces Hannibal Roy Bean, the one who successfully corrupted Chase.
Wuya successfully turned Raimundo against his friends by offering him power and respect after he felt snubbed by Master Fung near the end of the first season. Hannibal tried to corrupt Raimundo again but failed miserably.
HIM in The Powerpuff Girls could easily end the planet if he wanted to. He chooses his schemes based on tearing down the morality of the Girls, especially Bubbles, and admits defeat even when he doesn't have to, if the plan fails.