Douglas Costa de Souza (born 14 September 1990) is a Brazilian professional footballer who plays as a winger for Série A club Fluminense. He is known for his dribbling skills, speed, acceleration, and crossing ability.

Costa started his career with Grêmio, before moving to Shakhtar Donetsk in January 2010 for a fee of €6 million. He won numerous trophies with Shakhtar, including a domestic treble in the 2010–11 season (Premier League, the Ukrainian Cup and the Super Cup). In 2015, he joined Bayern for €30 million, where he won two consecutive league titles. He was loaned out to Juventus in 2017, and won a domestic double with the club in his first season. On 7 June 2018, Juventus made his loan move permanent; he added another two consecutive league titles in his next two seasons with the club, as well as a Supercoppa Italiana title. On deadline day of the 2020 summer transfer window, Costa returned to Bayern Munich on loan.

A full international since 2014, Costa represented Brazil at the 2015 Copa América and the 2018 FIFA World Cup.