Who invented McDonald's Filet-O-Fish sandwich in 1962?

Lou Groen invented McDonald's Filet-O-Fish sandwich in 1962.

Groen was a McDonald's franchisee in Cincinnati, Ohio, where his restaurant served a large Catholic population. During Lent, many customers avoided meat on Fridays, causing sales to fall. Groen responded by creating a fish sandwich that could fit McDonald's fast-service system.

The sandwich helped solve a local business problem while also expanding the McDonald's product range. Ray Kroc initially preferred a competing meatless product, but the Filet-O-Fish performed better in a test and was adopted by the chain. Its survival on the menu gave McDonald's a product associated with both seasonal demand and broader customer choice.

The Filet-O-Fish is sometimes described as a later seafood innovation, but its origin dates to 1962. Lou Groen's franchisee-led invention shows how McDonald's branding and menu history were shaped not only by headquarters, but also by local operators.