Jim Delligatti created the Big Mac.
Delligatti was a McDonald's franchisee in the Pittsburgh area who developed the sandwich in the 1960s. He wanted a larger menu item that could compete with substantial burgers sold by rival restaurants. The resulting sandwich used two beef patties, a middle slice of bun, cheese, lettuce, pickles, onions, and sauce.
The Big Mac was first introduced in 1967 at Delligatti's McDonald's restaurants. It became a national menu item in 1968 and eventually one of the most recognizable products in the McDonald's portfolio.
Ray Kroc is often mistakenly credited with inventing every famous McDonald's product because he led the company's expansion. In this case, the credited creator was franchisee Jim Delligatti, whose regional experiment became a global brand icon.