In 1941, Warner Brothers under the Merrie Melodies label released Goofy Groceries. I am not going to really review this cartoon because I am pretty sure its like "really ground breaking" and stuff and I am no expert on anything non-superhero of the era. Lets just say its basically the 1940's version of Toy Story in a grocery store, which does sound pretty cutting edge if I put it that way.
Anyways, after a few minutes of dancing soup cans and a monocle wearing potato taking a dip in the sink, a gorilla animal cracker freaked out. Turtle soup tanks and gingerbread paratroopers proved no match and finally "Superguy" leapt off of a box of soap chips. The doofus got scared and turned into a baby. And thus, we were given the first animated superhero parody. Interestingly, as far as I can tell, Goofy Groceries debuted in March of 1941 and Superman AKA The Mad Scientist on September, so this parody actually predated the animated Superman. How 'bout that?