Supervillains were originally created because superheroes felt too powerful to just fight ordinary criminals without powers. The first recurring supervillain was the Ultra-Humanite, who first appeared in Action Comics #13 as an enemy of Superman. Instead of having super-strength, the Ultra-Humanite relied on his intelligence and the ability to swap bodies in order to fight Superman.
Origins
In comic books, supervillains often gain powers as a result of a disastrous accident that either leaves them bitter about their new condition or inspired to use their new abilities to benefit themselves. Other supervillains may invent technology that gives them superpowers.
Motives
A supervillain is motivated to do evil for many purposes. They may want to rob banks, rule the world, or beat a superhero to prove themselves to the world.
For example, Lex Luthor hates Superman in modern comic stories because he is everything that Lex is not, and is bitter that humanity has to rely on an alien for protection. The Joker doesn't hate Batman, but he seeks to prove that everyone is only one small mistake away from becoming crazy just like him, and sees Batman as his natural foil.
Popular supervillains
There are many popular supervillains in comic books.
The Joker is a supervillain in Batman comic books. He is an evil clown who likes to rob banks and cause a general ruckus. His primary goal is to drive Batman past his no-killing rule, proving that "society" is nothing more than a "bad joke".
Lex Luthor is a supervillain in Superman comic books. In the Silver Age of Comic Books, Lex Luthor hated Superman because when they were teenagers, Superman(then known as Superboy) accidentally made Lex go bald after putting out a house fire which caused chemicals to burn Lex's hair away forever. In modern comics, Lex hates that humanity accepts Superman despite not being human.
The Green Goblin is a supervillain in Spider-Man comic books. Originally Norman Osborn, father of Peter Parker's best friend Harry Osborn, the Green Goblin was motivated to do evil out of a hatred for Spider-Man, and a desire to drive him insane, similar to the Joker.
Thanos is a supervillain in Avengers comic books. Originally appearing in an Iron Man book, Thanos is motivated to do evil out of devotion to Lady Death, and sometimes the goal of wiping out half of the universe with the Infinity Stones.
Doctor Doom is a supervillain appearing in Fantastic Four comic books. He is the ruler of the fictional country of Latveria, and has a burning hatred for Reed Richards because he is a threat to his intelligence. Doctor Doom is a master of technology and magic, ruling Latveria with an iron fist.
Magneto is a supervillain appearing in X-Men comic books. A survivor of the Holocaust, he is a mutant, and the leader of the Brotherhood of Evil Mutants. He has powers of magnetism, allowing him total control over all magnetic metals. He hates the X-Men because they stand in his way of making mutants the dominant force on Earth.
Harley Quinn is a supervillain appearing in Batman comic books. Originally appearing in Batman: The Animated Series, Harley Quinn was the Joker's right hand henchperson and abused "partner". She soon grew in popularity and started to appear in comic books of her own.
Darkseid is a supervillain appearing in Justice League comic books. The ruler of Apokolips, he is motivated to eradicate all free will in the universe and shape it to his own tyrannical will with the help of the Anti-Life Equation, a mathematical formula that supposedly proves that life is hopeless and that freedom is only a delusion.