The Ramos Gin Fizz has deep roots in New Orleans as it was created in the city and was made famous by Louisiana Governor Huey Long. It was originally created by Henry C. Ramos during prohibition. The creation of this drink is a pivot point in New Orleans drinking culture, created when alcohol was only available through nefarious means.
A man not of ill repute, but rather an average citizen with artistic inclinations created the drink. Being owner of the Imperial Cabinet Saloon on Gravier Street could have been a contributing factor, but it was his passion for mixing that lead him to create the iconic alcoholic beverage. There's a bit of a dispute, however, in the origin of the story. According to author of Mixing New Orleans: Cocktails and Legends Jenny Adams, "There is dispute over which brother created the Ramos Gin Fizz, with some accounts claiming Henrico C. Ramos as the mastermind and others celebrating the mixology of his sibling Charles Henry Ramos."
The drink's originally recipe, regardless, contained very few things: dry gin, powdered sugar, heavy cream, fresh lemon juice, lime juice, an egg white, and orange flower water. As legend goes the original recipe called for twelve minutes of shaking before being poured and mixed with soda water. The drink without question has an iconic history, but the creator will forever remain a mystery.
Adams added about the city that, "New Orleans is definitely a "cocktail" town. Good drinks, made properly with premium ingredients, are part of entertaining here."
Update: Changes to the story have been made in accordance with information from Adams.