The gyro sandwich is a popular Greek dish that is believed to have originated in Greece in the early 20th century. The word "gyro" comes from the Greek word "γύρος" (pronounced "yee-ros"), which means "turn" or "revolution", referring to the method of cooking the meat on a vertical rotisserie.

The exact origin of the gyro sandwich is somewhat disputed, but it is generally believed to have been created in Greece in the 1920s or 1930s. Some accounts credit the dish to a Greek immigrant named Nicholas Tselementes, who brought the concept of the Turkish doner kebab to Greece and adapted it to local tastes.

Others attribute the invention of the gyro to a different Greek immigrant, John Garlic, who opened a restaurant in Chicago in the 1960s and began serving a version of the gyro sandwich to his customers.

Regardless of its exact origin, the gyro sandwich quickly became a popular street food and fast-food item in Greece and later in other parts of the world, particularly in the United States. Today, the gyro sandwich is a ubiquitous food item that can be found in Greek restaurants, street vendors, and fast-food chains around the world.