3. Wheatley (Portal 2)
https://www.youtube.com/watch?v=wWRTS5A0l4Y Much like GLaDOS before him, Wheatley had truly earned his beating at the hands of the player. The humorous little sidekick that you took through the game took his opportunity to betray you and became one of the biggest jerks in gaming history, making his defeat an utter pleasure. Where the GLaDOS battle got its charm from her trail of insults and belittling of you, the Wheatley battle works on a much more pure level of fun. While Wheatley does spend a lot of time hurling verbal jabs at you, there's a crowning moment of pride when you defeat him that works so well. What looks like your end slowly turns into an epic use of the portal gun itself, a definitive moment of cool when you transport him to the surface of the moon and finally shut his mouth for good. There had been a lot of new uses for the portal gun throughout the sequel, including new surfaces to interact with, and it all comes together in this battle. It takes all of your skills that you've learned thus far to defeat him, allowing for a battle that is just insanely fun to play and will keep you coming back for more.