One factor is their motivation. If their motivation is purely self - centered and involves harming others on a large scale, they can be seen as very evil. Take Darth Vader from 'Star Wars' for instance. He was initially lured to the dark side by the promise of power, and in the process, he committed many atrocities, like destroying entire planets. However, his character also has some complexity as he later redeemed himself, but during his time as a Sith Lord, he was a symbol of great evil. Another aspect is their methods. Characters who use cruel and sadistic methods to achieve their goals are often regarded as evil. The White Witch from 'The Chronicles of Narnia' froze Narnia in eternal winter and turned many of its inhabitants to stone, showing her extreme cruelty.
Well, a character's disregard for moral and ethical boundaries makes them extremely evil in fiction. Think about Nurse Ratched from 'One Flew Over the Cuckoo's Nest'. She uses her position of power in the mental institution to control and break the patients. She is cold - hearted, manipulative, and her actions are aimed at suppressing the individuality and freedom of those in her care. She doesn't seem to have any sense of right or wrong, at least not in the way that benefits the patients, which is why she can be seen as an evil character.
Well, a character that is the most evil in fiction often has a goal that is inherently wrong and harmful. Like the White Witch in 'The Chronicles of Narnia'. She wants to keep Narnia in an eternal winter and kill all the Narnians who oppose her. Her actions are cold - blooded and her heart is filled with hatred. They also don't show any mercy or remorse for their actions. No matter how much pain and suffering they cause, they just keep on with their evil plans without a second thought.
If a villain enjoys inflicting pain and suffering on others without any remorse, they can be seen as extremely evil. Hannibal Lecter from 'The Silence of the Lambs' not only kills people but also eats them. He takes pleasure in the horror he causes, which is what makes him so terrifyingly evil.
One of the most evil characters in fiction is Lord Voldemort from the Harry Potter series. He is responsible for countless murders, including the death of Harry's parents. His goal was to take over the wizarding world and rule with an iron fist, eliminating all those who opposed him, especially Muggle - born wizards.
Power combined with a lack of morality. For example, if a powerful alien race in science fiction uses its advanced technology to enslave weaker races just for fun or to gain more resources without any ethical consideration. That's pure evil. They could be doing it on a large scale, across galaxies perhaps, and not care about the suffering they cause.
Their impact on the story and other characters is another factor. In 'A Song of Ice and Fire', Joffrey Baratheon is detested for his sadistic and cruel nature. His actions towards Sansa Stark and others are so heinous that his character is unforgettable. His evil drives much of the political and personal drama in the story.
The complexity of their evilness. Hannibal Lecter in 'The Silence of the Lambs' is not just a simple killer. He's highly intelligent, cultured, and yet has this dark side where he can be extremely cruel. His ability to manipulate those around him while being locked up in prison adds to his memorable nature.
Abilities are a big factor. For example, if a character can manipulate time like Doctor Strange in some Marvel stories. He can rewind, fast - forward or even create time loops, which gives him a huge advantage. Another aspect is intelligence. Characters like Batman, who don't have superpowers but are super - intelligent, can outwit most opponents.
A character can be the most tragic when they face impossible choices. For example, like Sophie in 'Sophie's Choice' who has to decide which of her children will live and which will die in a concentration camp. This kind of choice that goes against all human nature is a major factor in making a character tragic.
A character's power often depends on the context of their fictional world. In a world full of magic, like in 'Harry Potter', someone like Dumbledore is very powerful because of his great magical knowledge and skills. He can perform powerful spells and has a deep understanding of magic. But in a more science - fiction based world, a character like the Doctor from 'Doctor Who' is powerful because of his advanced technology and his ability to travel through time and space.
I think the most evil character in fiction is the Joker from Batman. He has no regard for human life, is unpredictable, and delights in chaos and destruction. His twisted mind and lack of a moral compass set him apart as a truly evil figure.