member of the General Foods
"horror" cereal trinity
that includes Count Chocula
Fruit Brute was a werewolf. His cereal was relatively short-lived (1974-1982) and arrived after my Mom had banned sugar cereals, so I can't vouch for its quality.
Source: Topher's Breakfast Cereal Character Guide (http://www.geocities.com/EnchantedForest/3278/cereal-generalmills.html).
Two strange assertions from that page: 1) Fruit Brute boxes appear in Quentin Tarantino movies; 2) There was a fifth cereal called Yummy Mummy, circa 1988. I can't say that name without laughing out loud, nor does it sound particularly yummy. No wonder it flopped.
See also Count Chocula Cereal node by devolver42.