Supergirl is an American superhero drama television series developed by Ali Adler, Greg Berlanti and Andrew Kreisberg that aired on CBS and later The CW from October 26, 2015, to November 9, 2021. Based on the DC Comics character created by Otto Binder and Al Plastino, the series follows Kara Zor-El (played by Melissa Benoist), Superman's cousin, and one of the last surviving Kryptonians from the planet Krypton. As Supergirl, Kara uses her powers to protect National City. The series was retroactively incorporated into the Arrowverse beginning with its second season, and became definitively linked with the rest of the franchise in the fifth season.

The series was officially picked up on May 6, 2015, after receiving a full series commitment in September 2014. Following a full season order on November 30, 2015, it transitioned to The CW for its second season going forward.

Supergirl received mixed-to-positive reviews from critics, with praise for its creative direction and cast performances (especially Benoist's), though its handling of political themes such as empowerment and social justice was criticized. It won the Most Exciting New Series at the 5th Critics' Choice Television Awards in 2015. The television series Superman & Lois was developed as a direct spin-off of Supergirl with Tyler Hoechlin and Elizabeth Tulloch reprising their Arrowverse roles; however, after COVID-19 restrictions led to a planned first season crossover with Supergirl being cancelled, creative redevelopment led to the series being retconned as being set in its own continuity from its second season onward, with no narrative ties to Supergirl, rendering it a stand-alone spin-off.