This is a list of current and former Major League Baseball mascots, sorted alphabetically.
The tradition in the Major League Baseball mascot began with Mr. Met, introduced for the New York Mets when Shea Stadium opened in 1964. Although some mascots came and went over time, the popularity of mascots increased when The San Diego Chicken started independently making appearances at San Diego Padres games in 1977. Philadelphia Phillies management felt they needed a mascot similar to the Chicken, so they debuted the Phillie Phanatic in 1978.
All but three major-league teams have "official" mascots (Dodgers, Yankees, and Angels). Seven team mascots – Sluggerrr (Kansas City Royals), the San Diego Chicken, the Phillie Phanatic, Mr. Met, the Oriole Bird, Slider (Cleveland Guardians), and Southpaw (Chicago White Sox) – have been inducted into the Mascot Hall of Fame. Several others have been nominated since the Hall's creation in 2005.
Mascots in MLB are often used to help market the team and league to young children.