A Bloody Mary is a savory cocktail built on vodka and tomato juice, seasoned with ingredients such as Worcestershire sauce, Tabasco, lemon juice, salt, and pepper, and garnished with a celery stalk. It's believed to have evolved from the Red Snapper, a similar drink served in 1920s Paris, and to have taken its now-familiar form in the 1930s at the St. Regis Hotel in New York, credited to bartender Fernand Petiot.
Beyond the base recipe, Bloody Marys are commonly customized with horseradish, pickle juice, olives, or bacon, aiming for a savory, umami-rich profile that balances the tomato juice's acidity. They're typically served chilled and are a fixture of brunch menus, partly on the folk belief that a savory, alcoholic drink eases a hangover.
Several drinks are close relatives rather than the same thing: a Bloody Caesar swaps in clamato juice, a Bloody Maria uses tequila instead of vodka, and a Bloody Bull replaces some or all of the tomato juice with beef broth or bouillon. A non-alcoholic version built the same way is usually called a Virgin Mary.