So, we've got our protagonists and are ready to write our story. Or are we? If you have crafted a great protagonist, it is only fitting that you now make an antagonist that will challenge our newly minted protagonist. So, what goes into making an awesome antagonist that will give your hero a run for their money?

Archetypes: The Villain Edition

Remember when we were crafting our heroes and talked about archetypes? Well, there are archetypes that fit in the scope of your antagonist.

The Ruler - Who doesn't love a despotic ruler? For them power isn't just a thing, it is the ONLY thing. This is the type of villain that loves to grind his opposition under his bootheel but more than likely does it through other agencies rather than himself. Examples include King Joffrey of GOT, Ming the Merciless of Flash Gordan, and Sebastian Shaw of X-men.
The Temptress - The Temptress can be the ultimate spy or assassin. This is a female dominated archetype but that doesn't mean that there aren't men that are Temptresses. This archetype focuses on subterfuge and manipulation rather than brute force. Examples include The Evil Queen from Snow White, Emperor Palpatine from Star Wars, The Enchantress from Thor.
The Trickster - This is another archetype that depends on trickery and manipulation rather than brute force. While the Temptress relies on sex appeal and charm, the Trickster is an archetype of traps and plans. Examples include The Riddler from Batman, Sweet from Buffy the Vampire Slayer (Demon summoned during the episode "Once More with Feeling"), and Loki from the MCU.
The Fanatic - This archetype is the least likely to be swayed by arguments from the protagonist. This is the archetype of the believer that knows their actions are for the greater good and is willing to go any distance to achieve their goal. Many serial killers fall under this archetype. Examples include John Doe from Se7en, Ra's al Ghul from Arrow, and the Operative from the movie Serenity.
The Betrayer - Also known as the Heretic or the Traitor, this is the archetype that betrays their faith and ideals. They now fight against those things they hold dear. Examples include Horus from Warhammer 40k, Darth Vader of Star Wars, and the Warlock Lord from the Shannara Chronicles.
The Beast - This is the monster archetype, one of unending hunger and rage. This is one of the simplest archetypes to write as it is usually limited in intelligence. Examples include Doomsday from Superman, Moby Dick from the book of the same name, and the Balrog from Lord of the Rings.
The Mastermind - The planner or plotter. Usually, in control of several minor antagonists, he uses them to execute his plan to gain his goal. Examples include Captain Cold from Flash, Moriarty from Sherlock Holmes, and Keyser Soze from the Usual Suspects.
The Corrupted - The once good fallen into the role of villain. This could have many catalysts. Disillusionment. Mind-control. The list goes on. Examples include Harvey Dent from Batman, Macbeth from Macbeth, and Saruman from Lord of the Rings.
The Dark Knight - These are characters that believe they are heroes. They take a very extremist view of the vigilantism they may perform and are usually willing to kill for what they believe in. Most will adhere to a strict moral code that only they truly understand. Examples include Col. Nathan Jessup from A Few Good Men, Vigilante from Arrow, and Ozymandias from the Watchmen.
The Devil - This archetype is for those that are the personification of evil. Dark gods, demons, etc... Examples include Pennywise the Clown from IT, Lucifer from Supernatural, and Wednesday from American Gods.
The Mercenary - This is a person whose sole motivation is to be paid. Their services are to the highest bidder and so sometimes they can be defeated without bloodshed. Examples include Bullseye from Daredevil, Deathstroke from New Teen Titans, and Boba Fett from Star Wars.
The Minion - These are the characters that are servitors of some Dark Lord. Examples include The Terminator, Xenomorphs from Alien, and Ronan the Accuser of Guardians of the Galaxy.

The Catalyst

This is a part of the antagonist creation that you do not necessarily share with the readers. The catalyst is the event that made the antagonist a villain. So, why is this important, especially if you aren't going to share this information with the reader?

The catalyst is something that informs every action of your antagonists. Magneto does what he does because of the concentration camps of Nazi-occupied Poland. His catalyst shows in every single one of his actions. And remember, just because you don't immediately share an antagonist catalyst, doesn't mean you won't. Down the road, if you do share the catalyst, you will be glad that you thought of it at the beginning to keep the character more consistent.

What goes into a good catalyst, though? Well, here are several types of catalysts that will help shape your antagonist:

Tragedy - One of the most basic types of catalysts, such an event can make a villain of even the best person. Mostly this catalyst is instigated by the death of a loved one.
Abused - The antagonist was abused in some way and that turned them down the dark path of villainy.
Corruption - This catalyst is the whispered word within a character's ear. Too late, the character finds out that he has gone down a dark and unredeemable path.
Mind-controlled - This villain finds themselves under the direct control of another. This could be from an object, event, or person.
Indebted - The antagonist finds themselves owing someone a debt that they cannot get out. This is a common theme in Supernatural.
Born to Evil - Maybe one of the simplest catalysts, the antagonist was born evil.
Fulfilling a Need - This is a catalyst that is very tricky because your antagonist is not necessarily dark, just desperate. Look at Mr. Freeze from Batman, his sole purpose is to find a way to revive and save his wife. Nothing else matters and he's willing to do whatever to accomplish his goals. But he doesn't do anything that isn't directly related to saving his wife.

Now, when you are crafting your villain's catalyst, usually the best ones are stories that we can empathize with. What makes Magneto such a great villain is that we immediately understand why he is doing the things he does. We can see ourselves in his actions and, at some deep level, this frightens us because the line between good and evil is much thinner than we ever imagined. That is something you should strive to do with your antagonist, make them a dark mirror that shows us ourselves.

Avoid being a villain apologist when writing these catalysts and eventually backstories. Such stories are given resonance when it is a decision that is fully in the antagonist's hands that leads them down the dark path. Remember that these are catalysts, they are the events that made a character a villain and are not necessarily something that is still happening. A mind-controlled antagonist could have broken the mind-control but decided that he liked feeling powerful as only he could when he is a villain.

Eventually, every villain must be given the responsibility of their actions.