Breanna Mackenzie Stewart (born Baldwin; born August 27, 1994) is an American professional basketball player for the New York Liberty of the Women's National Basketball Association (WNBA).

In high school, Stewart was the National Gatorade Player of the Year, the Gatorade Female Athlete of the Year, and a McDonald's All-American. She led the University of Connecticut Huskies to four national championships, was named the Final Four's most outstanding player a record four times, and was a three-time consensus national player of the year. Stewart was the first overall pick in the 2016 WNBA draft and was named the 2016 WNBA Rookie of the Year. She was named the WNBA MVP in 2018 and was named an All-Star in 2017, 2018 and 2021. She led the Storm to two championships in 2018 and 2020, and received the WNBA Finals MVP award both times. In 2021, Stewart was named to The W25 as one of the top 25 players of the WNBA's first 25 years.

As a member of the U.S. women's national team, Stewart has won gold medals in the 2016 and 2020 Olympics and at the 2014 and 2018 FIBA World Cup.