Brian McGuire Cashman (born July 3, 1967) is an American baseball executive for the New York Yankees of Major League Baseball (MLB). He has served as the general manager and senior vice president of the Yankees since 1998. During Cashman's tenure as general manager, he inherited a core that was built by Gene Michael and Bob Watson, the Yankees have won seven American League pennants and four World Series championships.

Cashman began working with the Yankees organization in 1986 as an intern while still in college. He was named assistant general manager in 1992, helping to run the team while owner George Steinbrenner was suspended from baseball. He succeeded Bob Watson as the team's general manager in 1998.

Cashman was born in Rockville Centre, New York, and raised in Washingtonville, New York. He was raised in an Irish Catholic family, as the middle of five children born to Nancy and John Cashman. He became a baseball fan at a young age, attending a summer camp hosted by Bucky Dent before starting high school. He grew up as a fan of the Los Angeles Dodgers. While visiting his grandmother in Florida, he served as a batboy for the Dodgers during spring training in 1982, with the help of former Dodger Ralph Branca, a family friend.

The Cashman family moved to Lexington, Kentucky, where his father managed Castleton Farm, raising standardbreds for harness racing. Cashman described moving out of Washingtonville before starting high school as "the best thing to happen to [him], to get out of there."

Cashman attended Lexington Catholic High School before moving to the Washington, D.C., metropolitan area. He attended Georgetown Preparatory School in North Bethesda, Maryland, graduating in 1985. Cashman played baseball and junior varsity basketball at both schools, and added football in his senior year. Brian was classmates with Supreme Court Justice Neil Gorsuch and two years after future Supreme Court justice Brett Kavanaugh.

The Catholic University of America offered Cashman the opportunity to play college baseball for the Catholic Cardinals, competing in the National Collegiate Athletic Association's Division III, guaranteeing him playing time as a freshman. He was a four-year starter at second base and the team's leadoff hitter. He set a school record for most hits in a season, which has since been broken. He earned a bachelor's degree with a major in history in 1989.

George Steinbrenner, the owner of the New York Yankees, met John Cashman when he managed Pompano Park in Pompano Beach, Florida, and the two became friends. Through another family friend, John helped Brian obtain a position with the Yankees organization as an intern in 1986. He worked in the minor league scouting department in the day, and worked security at night. After Cashman graduated from Catholic, the Yankees offered him a position as a baseball operations assistant, which he accepted.

Steinbrenner was banned from baseball in July 1990 for hiring a gambler to investigate Dave Winfield. Gene Michael, then the Yankees' general manager, took over daily operations of the Yankees, and Cashman played a role in assisting him. He was promoted to assistant farm director that year, and to major league administrator in 1991. Michael named Cashman an assistant general manager in 1992. He remained in the role after Bob Watson succeeded Michael as general manager in 1995. The Yankees won the 1996 World Series.