sentences:  Jennifer Aniston, Richard Belzer,
  Natasha Henstridge, Norman Lear, and Peter Serafinowicz have guest starred as other speaking characters.During "South Park"'s earliest seasons, several high-profile celebrities inquired about guest-starring on the show.As a joke, Parker and Stone responded by offering low-profile, non-speaking roles, most of which were accepted; George Clooney provided the barks for Stan's dog Sparky in the season one (1997) episode "Big Gay Al's Big Gay Boat Ride", Leno provided the meows for Cartman's cat in the season one finale "Cartman's Mom Is a Dirty Slut", and Henry Winkler voiced the various growls and grunts of a kid-eating monster in the season two (1998) episode "City on the Edge of Forever".