Phoebe Cates plays the role of Elizabeth in Drop Dead Fred .
British comedian Rik Mayall stars as the title character , a happy , anarchic and extremely mischievous imaginary friend of a young girl named Elizabeth ( Phoebe Cates ) and arch nemesis of her fussy and overbearing mother Polly ( Marsha Mason ) whom he refers to as the `` mega bitch '' .
Drop Dead Fred