Michael Delligatti, who was known as "Jim," invented the Big Mac. AP The inventor of McDonald's iconic Big Mac has died.

Michael Delligatti, who was known as "Jim," died Monday night in Pittsburgh at the age of 98.

Delligatti was one of McDonald's first franchisees.

He made an indelible impact on American cuisine with the creation of the Big Mac burger in 1967 at his Uniontown, Pennsylvania restaurant.

Delligatti made the sandwich by combining two all-beef patties, lettuce, cheese, pickles, and onions, as well as a "secret sauce."

That's the same recipe that's used today for the Big Mac sandwich, which is served in more than 100 countries worldwide.

Delligatti also played an integral role in the development of McDonald's breakfast menu, by creating the Hotcakes and Sausage meal to feel steel workers at the end of their overnight shifts, according to an obituary written by his family that was provided by McDonald's.

Delligatti at a celebration for his 90th birthday. AP He opened his first McDonald’s restaurant in 1957 and went on to operate 47 additional locations in Pennsylvania.

"Jim was a legendary franchisee within McDonald’s system who made a lasting impression on our brand," McDonald's said in a statement on Delligatti's death. "We will remember Jim as an insightful franchisee, a knowledgeable businessman, and an honorable gentleman who left a legacy of four generations of family members running great restaurants in Pennsylvania and North Carolina."