Linus was the mascot for Crispy Critters, "the one and only cereal that comes in the shape of animals." Whenever Linus would mention the name Crispy Critters, there would be a stampede.
The commercials were popular enough to be spun off into a series
Linus was joined by other cereal mascots such as the Sugar Crisp Sugar Bear and the Alpha Bits mailman names, I kid your not, Lovable Truly.