Peter Paul Montgomery Buttigieg ( BOO-tij-əj; born January 19, 1982) is an American politician and former naval officer who is serving as the 19th United States secretary of transportation. A member of the Democratic Party, he served as the 32nd mayor of South Bend, Indiana, from 2012 to 2020, which earned him the nickname "Mayor Pete".

Buttigieg is a graduate of Harvard College and the University of Oxford, attending the latter on a Rhodes Scholarship. In 2007, he began three years of work at the management consulting firm McKinsey & Company. From 2009 to 2017, he was an intelligence officer in the United States Navy Reserve, attaining the rank of lieutenant. He was mobilized and deployed to the War in Afghanistan for seven months in 2014. Before being elected as mayor of South Bend in 2011, Buttigieg worked on the political campaigns of Democrats Jill Long Thompson, Joe Donnelly, and John Kerry, and ran unsuccessfully as the Democratic nominee for Indiana state treasurer in 2010. While serving as South Bend's mayor, Buttigieg came out as gay in 2015. He married Chasten Glezman, a schoolteacher and writer, in June 2018. Buttigieg declined to seek a third term as mayor.

Buttigieg ran in the 2020 Democratic Party presidential primaries, launching his campaign for the 2020 presidential election on April 14, 2019. He became one of the first openly gay men to launch a major party presidential campaign. Despite initially low expectations, he gained significant momentum in mid-2019 when he participated in several town hall meetings and television debates. Buttigieg narrowly won the Iowa caucuses and placed a close second in the New Hampshire primary. By winning Iowa, he became the first openly gay candidate to win a presidential primary or caucus. Buttigieg dropped out of the race on March 1, 2020, and endorsed Joe Biden the following day.

President-elect Biden named Buttigieg as his nominee for Secretary of Transportation in December 2020. His nomination was confirmed on February 2, 2021, by a vote of 86–13, making him the first openly gay Cabinet secretary in U.S. history. Nominated at age 38, he is also the youngest Cabinet member in the Biden administration and the youngest person ever to serve as Secretary of Transportation. Press reports had mentioned Buttigieg as a possible running mate for Kamala Harris upon the start of her 2024 presidential campaign, though he was ultimately not selected.