But McDonald's Filet-O-Fish is also a wildly popular fast food item with a colorful origin story. Created out of a necessity for the meatless Fridays of Lent, the Filet-O-Fish got its start as a part of a cooking competition in the 1960s. The Filet-O-Fish beat out a fruit-centric pineapple pattied Hula burger, and quickly became an instant hit with Lent-observing Christians.