Wendy's

Dave Thomas opened the first Wendy’s in Columbus, Ohio, in November 1969 and named it after his daughter Melinda, whose childhood nickname was Wendy. His big idea was that fast food did not have to mean frozen and flavourless, and his most visible idea was the square patty: the corners stick out past the round bun so you can see the beef, and the company still repeats his line that Wendy’s does not cut corners.

Wendy’s also built one of the first drive-thru pick-up windows and invented the Frosty, the half-milkshake, half-soft-serve that people dip their fries into. These days it is as famous for its sarcastic social media as for its burgers, but the burgers are the reason the jokes land.

Around 7,000 restaurants, most of them in the United States, and a growing presence in the UK.

• Checkers & Rally's (United States, since 1986). Two names, one menu, double drive-thrus and fries everyone argues about. Also built on beef, bacon, cheese and a double stack.
• Dairy Queen (United States, since 1940). The ice cream chain that quietly sells a lot of burgers, especially in Texas. Also built on beef, bacon, heat and cheese.
• Fatburger (United States, since 1947). The Last Great Hamburger Stand, founded by a woman and immortalised in hip-hop. Also built on beef, bacon, cheese and a double stack.
• Hardee's (United States, since 1960). Biscuits in the morning, Thickburgers the rest of the day. Also built on beef, bacon, cheese and a double stack.