Note: Bloo was mentioned by Eric Cartman in the South Park trilogy episode Imagination Land as well as making a cameo appearience briefly. He is the only character to appear in every episode of the series. He became increasingly mischievous over the run of the series and can be a show-off. Bloo loves paddle-balls even though he cannot make the ball hit the paddle (though the only time he was able to do it was in the episode 'Let Your Hare Down').
Despite all this, he still has a good heart and apologizes for his actions. Bloo is often very self-centered, egotistic, narcissistic, and occasionally sociopathic as well as having a knack for getting in trouble. Mac's 5-year-old imaginary friend and best friend who resembles a simple, domed cylinder.
He takes delight in bullying Mac and making his life miserable.