The original Chewits advertisements featured the ‘Monster Muncher’, a Godzilla-resembling mascot on the hunt for something chewy to eat.  But the ‘Monster Muncher’ could only be quelled by a pack of Chewits. They used claymation special effects, and also included a voiceover style reminiscent of a 1950s radio serial.

“Run for your lives, the muncher is coming!
He’s eating everything in his path.
It is the end of civilisation as we know it.
Not quite professor, it’s a long shot, but it might just work.
Come back Chuck!
Chewits, even chewier than a 15-storey block of flats.”