Matter Ingestion – The ability to consume many sorts of matter without any ill effects on the user.
Matter-Lad (DC) has this power and this is only superpower. Superman (DC) had better pray Matter-Lad never becomes a zombie.
Matter Lad goes insane after eating the Miracle Machine in Legion of Super-Heroes V1 #251. Superman (DC) had better pray Matter-Lad never becomes a zombie.
The Shi’ar Imperial Guard Glom (Marvel) is a parody of Matter-Lad.
In Action Comics V1 #454, Superman eats a zillion hamburgers.
In New Super-Man #5 (DC), the New Super-Man eats a lot of Chinese food.
Superman eats Kryptonite in the Sandman Saga (Superman V1 #233).
Doctor Odd ingests an enemy in Pantheon #12 (Lone Star Press).
Aurumkvorax – TSR 2140A Monstrous Manual
Charfiend – Creature Collection I
Dalmosh – D&D 3.5 – Monster Manual V
Demon Scum – Cyberforce – Sourcebook #2
Eatle – Ben 10
Gauntling – Creature Collection II. Dark Menagerie
Korumbu (Marvel) causes a man to be able to eat as much as he likes or in this does not like in Journey into Mystery V1 #64.
Jimmy Olsen (DC) can eat just about anything in Jimmy Olsen #38.