Sid - Sid the Sloth is a Megatherium shown in all three films as one of the main characters. Sid is portrayed as unattractive, unfit, and unintelligent. While he is always called 'Sid,' Sid's full name is 'Sidney,' as revealed by his would-be paramour, Sylvia (who pursued him throughout one version of the first movie's plot). Sid is voiced by John Leguizamo.