There are two versions of the origin of Eggs Benedict.
The first is about a lady named Mrs. LeGrand Benedict, who couldn't find anything to her liking on the menu at Delmonico's Restaurant (the first public restaurant in the U.S.) The chef, Charles Ranhofer, came up with what he called Eggs a' la Benedick and published it in his cookbook in 1984.
The second and way more interesting story, is about a man named Lamuel Benedict. An article appeared in the December 19th, 1942 issue of the weekly New York magazine "talk of the town" column....and is based on an interview with Lemuel the year before he died. In 1894, Lemuel Benedict, a wall street broker, who was suffuring from a hangover, ordered "some buttered toast, crisp bacon, two poached eggs, and a hooker of hollandaise sauce" at the Waldorf Hotel in New York. The Waldorf's legendary chef Oscar Tschirky was so impressed that he added it to his menu after substituting canadian bacon for the crisp bacon, and an English muffin for the toasted bread.
So you can decide for yourself which story is more believable, although if you have ever had Eggs Benedict on a hangover, I'm sure you will be on Lemuel's side!