Hamburger Hamlet or "The Hamlet", was a chain of restaurants based in Los Angeles, a point of reference for Angelenos and for the creative industries that were located in the city. Opened in 1950, it grew to a chain of 24 locations, including Chicago and the Washington, D.C. metro areas. before they were all either sold or closed down. The restaurants served hamburgers topped with what were considered exotic combinations of toppings, such as a bacon cheeseburger with Russian dressing. A famed side dish were the "little fried onions". Tomato relish was provided at each table. They also served omelettes and Mexican dishes. In 1968 the Lewises opened upscale restaurant Kate Mantilini. In 1987 Koo Koo Roo bought 14 Hamlet locations for $33 million. In Hollywood biographies of both Peggy Lee and Alfred Hitchcock, Hamburger Hamlet is mentioned as a favorite haunt. In the novel American Dream Machine, author Matthew Specktor mourns the closing of the Sunset Boulevard Hamlet as the passing of a bygone era of Old Hollywood glamour. In 2014, Los Angeles Magazine published the article Vintage Los Angeles: The Tragedy of Hamburger Hamlet, where author Alison Martino wrote:
It was where you bumped into celebrities and industry moguls in a casual environment, dining in darkly lit giant red leather chairs. But there was nothing casual about the clientele. Where else could you see Dean Martin sipping a martini at the bar, Lucille Ball hair spraying her red locks in the ladies room, Bette Davischain smoking in the Tap Room, or Frank Sinatra taking a meeting with his publicist? I witnessed all of this first hand. Even the restaurant’s hostess, actress and singer Frances Davis, who was once married to Miles Davis, would occasionally burst into song and dance while taking you to your table. I remember Francis and Diahann Carroll discussing chord progressions in the lobby.
In an era when putting bacon and cheese on a burger was considered luxuriantly deluxe, Hamburger Hamlet topped its burger with guacamole, baked beans and marinara sauce. They served a burger with jalapeños on garlic toast. The "Emperor Henry IV" burger came with ham, bacon and Russian dressing. As far back as 1977, the restaurant was even serving a bunless burger for the carb conscious.