He is the alter ego of Brennan Huff (also played by Will Ferrell), a 40-year-old man-child who lives with his father and struggles to find his place in the world. When Brennan's father remarries, Brennan's new stepbrother, Derek (played by John C. Reilly), comes to live with them, creating chaos and hilarity.
Buzz Killington is Brennan's fantasy persona, a rock star with a flamboyant personality and a love for partying. He is introduced in a scene where Brennan is trying to impress a woman by pretending to be a famous rock star.
Buzz Killington is a memorable character due to his over-the-top personality, which is a direct contrast to Brennan's awkward and childish behavior. He is a running gag throughout the movie, representing Brennan's desire for attention and his escape from reality.