Darth Vader

Darth Vader was a Dark Lord of the Sith, apprentice under Darth Sidious/Emperor Palpatine. Generally considered the most powerful Sith warrior in Star Wars canon, Darth Vader is a staple of villain iconography. He is commonly ranked among the finest villains ever created. He has appeared in a variety of villain wars, to varying degrees of involvement.

Vs Kerrigan
Darth Vader emerges in the epilogue of Video Game Villains Round Four, taking up the mantle of leadership of the Space Resistance upon the death of Saren. Prior to Round Five, Vader establishes a plan to dethrone Kerrigan as ruler of the galaxy.

Due to Kerrigan's forces being distracted by a large battle outside her doorstep, the Queen of Blades does not notice Darth Vader's arriving in her headquarters. The Sith Lord commands that she bow before him, but not before being attacked by a puppet version of Kerrigan controlled by SHODAN, Kerrigan's chief ally. Vader destroys this copy easily enough, then attempts to crush Kerrigan with a massive metal pillar. Kerrigan survives, knocking Vader through several walls in retaliation. Vader survives, destroying the massive Zerg Kerrigan is riding in a second attack. Kerrigan manages to get in a few good strikes, though Vader manages to shrug off most of the damage. The two eventually clash with their telekinetic abilities, with neither able to get a strong hold on the other. Resorting to final measures, Darth Vader hacks off both Kerrigan's wings, ultimately impaling her through the chest. Kerrigan does not survive the blow and succumbs to her injuries.

A New Emperor
With his new position as Emperor of the Galactic Empire in place, Vader seeks to consolidate his rule over the galaxy. He has his two new apprentices, Komari Vosa and Desann, collect some technology from the corpse of Saren. Unfortunately for Darth Vader, the two Sith perish to rival Sith Lords Darth Vindican and Darth Malgus. Now without an apprentice, Vader schemes a new plan to tighten his control. Suddenly, Dark Samus emerges as a potential ally.

Trivia

 * It is questionable whether or not Darth Vader applies for Video Game Villains War, due to his originally being a movie villain. dagwood525 justifies this due to most of the video games Vader stars in not being canon to the actual Star Wars movie universe.