Tuesday Terror Trivia for 7/20!

In the 1970s a breakfast cereal was introduced to capitalize on kids' obsession with all things monstrous. A cadre of strange creatures were the mascots for this product, and they lived in a dark, mysterious forest under a magical tree, said tree producing the sugary breakfast food you were certain to consume that morning. Now, I don't want to know the name of the product (that would be too easy, and we are NEVER about easy here). Who was the legendary Hollywood character actor who narrated the extended TV commercial that introduced these little monsters to the public? (He would go on to become a reliable presence in many upcoming Horror films of the decade.)