Astronomy Domine by 'The Pink Floyd, a pop group' (thanks to redstarrobot) showing Syd Barrett at his best 'Oberon, Miranda...' Hans Keller at the start and the end is almost incredibly pompous 'I don't want to prejudice you, but four quick points I want to make'. You don't have to be a fan of the music to think he's a dick.
Peter Cook in Bedazzled. Cook is Satan, stealing Dudley Moore's fandom by being a performer of pure evil. Cook was a great mimic, and in this he mimics pop star. Eleanor Bron and Dudley Moore support this performance very well. This is a scene that I often think about, and it's nice the way these iconic clips are now accessible.