Malty S Melromarc/Witch (Rising of the Shield Hero)
Silver Coin of Judas (Sleepy Hallow)
Lord Voldemort (Harry Potter) caused Quirinus Quirrell and Peter Pettigrew to betray their allies and serve him instead.
The Orb (Marchen Awakens Romance) corrupted the benevolent witch, Diana's mind and persuaded her to abandon her homeland. Together the two formed the Chess Pieces and began their first steps in taking control of the world of MÄR.
Peta (Marchen Awakens Romance) was able to charm the leader of Luberia, Galian into joining the Chess Pieces by offering him power. After being recruited, Galian abandoned any care he had left for Luberia and allowed Peta to destroy the guild and everyone in it.
Orochimaru (Naruto) caused Sasuke Uchiha to betray Konohagakure by promising him power.
Sakazuki/Akainu (One Piece) has a talent for manipulating his enemies. During the Marineford War, he convinced Squard into believing Whitebeard had betrayed all his allies.
Donquixote Doflamingo (One Piece) caused many of his victims to betray their saviors, the Straw Hat Pirates, by offering them a bounty-hunting game with huge monetary rewards.
Kaido (One Piece) made Hawkins and Apoo betray Kid's alliance once he appears.
Jadis (The Chronicles of Narnia) induced Edmund Pevensie to betray his siblings via sweet talk, enchanted food, and empty promises.
As a bond-severing god, Shaga (Good Luck Girl!) can turn the best of friends and closest of allies, into the bitterest and most hated of enemies.
Darth Sideous (Star Wars) charmed Anakin Skywalker with his knowledge of the dark side causing him to betray the Jedi council and join the Sith.
Discord (My Little Pony Series) used his magic to corrupt Twilight's friends, causing them to turn against one another.
Malty S Melromarc (Rising of the Shield Hero) ability to manipulating others into fighting each other and aiding her in her selfishness has earned her the name "Witch".