Scooby's Laff-A Lympics (1977)

Season 1: Episode 34

Lurking in Big City is The Shadowman, who mysteriously knows all of the plans of The Crime Commission. The Daring Duo are called in when the 700-karat Shmope Diamond is swiped. As they respoind, they spot a shadow sneaking off with plates for new $20 bills stolen from an armored car. The Shadowman later manages to kill two birds with one stone by making off with a secret gold shipment and framing Mayor Gaunt (who is captured in The Dyno Bad Guy Box) all in one shot.