Mayall studied drama at Manchester University and gained fame by appearing at The Comedy Store in the Eighties along with Edmondson. They starred as "The Dangerous Brothers", supposedly a couple of naive but anarchic daredevils, and would perform comedy stunts on stage, often involving the likes of setting each other on fire. They effectively brought slapstick to the alternative comedy scene, albeit in a typically extreme fashion.
A role as Rik in The Young Ones sitcom, also in the Eighties, ensured wide public acclaim. The series was written by Ben Elton, a long-standing friend. More recently he's starred in Bottom, again with Adrian Edmondson (in which the two of them effectively reprised their roles in The Young Ones), although he also did solo work such as several series playing Tory MP, Alan B'stard, in the sitcom The New Statesman. He has also appeared in films, notably Drop Dead Fred.