The “skinny margarita” as a lighter, lower-calorie take on a margarita does not have a single, clearly documented inventor, but the best-known popularizer of the concept and name in modern pop culture is Bethenny Frankel, who created the branded Skinnygirl Margarita in 2009. At the same time, bartenders and bars were serving “lighter” or “skinny” style margaritas before that, so the idea itself predates her; she mainly turned it into a packaged product and marketing phenomenon rather than inventing the drink category from scratch.