Performance by an Actress in a Supporting Role is one of the Academy Awards of Merit presented annually by the Academy of Motion Picture Arts and Sciences (AMPAS) to recognize an actress who has delivered an outstanding performance while working within the film industry. Since its inception, however, the award has commonly been referred to as the Oscar for Best Supporting Actress. While actresses are nominated for this award by Academy members who are actors and actresses themselves, winners are selected by the Academy membership as a whole.

Throughout the past 76 years, accounting for ties and repeat winners, AMPAS has presented a total of 76 Best Supporting Actress awards to 74 different actresses. Winners of this Academy Award of Merit currently receive the familiar Oscar statuette, depicting a gold-plated knight holding a crusader's sword and standing on a reel of film. Prior to the 16th Academy Awards ceremony (1943), however, they received a plaque. The first recipient was Gale Sondergaard, who was honored at the 9th Academy Awards ceremony (1936) for her performance in Anthony Adverse. The most recent recipient was Octavia Spencer, who was honored at the 84th Academy Awards ceremony (2012) for her performance in The Help.

This is a list of awards for supporting actor. These are accolades given by a group of film or television professionals in recognition of the work of supporting and character actors. Most awards for supporting actors are gender-specific.

A supporting actor is an actor who performs roles in a play or film other than that of the leads.

These roles range from bit parts to secondary leads. They are sometimes but not necessarily character roles. A supporting actor must also use restraint not to upstage the main actor/actress in the play/movie. In earlier times these were often ethnic stereotypes. The title is usually specific to the performance, that is, a person may be a supporting actor in one film and the leading actor in the next. An individual who typically plays supporting roles is considered a character actor.

In television, a day player refers to most performers with supporting speaking roles hired on a daily basis without long-term contracts.

Supporting roles may be pivotal or vital to the story. In recognition of important nature of this work, the theater and film industries give separate awards to the Best Supporting Actor and actress. A supporting actor/actress can also be known as a 'sidekick'.