King Dedede is the main villain in the Kirby series. He's gone toe-to-toe with Kirby in several games, including Kirby's Adventure, Kirby's Avalanche, Kirby Super Star, and more! Dedede also appears as a playable character to help Kirby in Kirby 64: The Crystal Shards, and as an unlockable character in Kirby Canvas Curse. He also got to join Kirby and Meta Knight as a playable character in Super Smash Bros. Brawl.
Most likely thanks to his Brawl appearance, Dedede made it to the Summer 2008 Contest, where he and Pit were both destroyed by Ryu Hayabusa and Zero. Dedede performed well enough in the Nomination Rally Tournament right before Character Battle X to return to the field, where he gave Revolver Ocelot a much better fight than his 2008 performance but didn't pull through.