John William Harbaugh (/ˈhɑːrbɔː/ HAR-baw; born September 23, 1962) is an American professional football coach who is the head coach for the Baltimore Ravens of the National Football League (NFL). Previously, he coached the defensive backs for the Philadelphia Eagles and served as the Eagles special teams coach for nine years. Harbaugh and his younger brother, former San Francisco 49ers and current Los Angeles Chargers head coach Jim Harbaugh, are the first pair of brothers in NFL history to serve as head coaches. Jack Harbaugh, Jim and John's father, served 45 years as a college defensive coach, an assistant coach, and a running backs coach. John and the Ravens beat Jim and the 49ers at Super Bowl XLVII in New Orleans on February 3, 2013, by a score of 34–31.

Harbaugh has led the Ravens to over 185 wins (including playoffs) since his tenure began in 2008, the third-most wins in the NFL over that span, and has surpassed Brian Billick for the most wins by a head coach in Baltimore Ravens franchise history. In his sixteen-year tenure as Ravens head coach, Harbaugh has led the Ravens to twelve winning seasons and only two losing seasons. His 22 playoff game appearances are the second-most by any head coach in the NFL since 2008. He is also the only head coach in NFL history to win a playoff game in six of the first seven seasons of a coaching career and has the most road playoff wins by a head coach (8). Outside of winning Super Bowl XLVII, Harbaugh has guided the Ravens to six AFC North division championships, four AFC Championship appearances and a franchise-best 14–2 record in 2019.

John Harbaugh was born in Toledo, Ohio, to Jackie Cipiti and Jack Harbaugh. John Harbaugh graduated from Pioneer High School in Ann Arbor, Michigan, during which time his father Jack was an assistant under Bo Schembechler at the nearby University of Michigan.

Harbaugh attended college and played varsity football as a defensive back at Miami University, where he graduated in 1984.

Harbaugh worked as an assistant at Western Michigan (1984–1986), Pitt (1987), Morehead State (1988), Cincinnati (1989–1996), and Indiana (1997).

He was first hired in the NFL in 1998 by the Philadelphia Eagles' then head coach Ray Rhodes, and was one of four assistant coaches retained by new head coach Andy Reid in 1999. As such, he is in the Sid Gillman coaching tree. In 2004, he was mentioned as a possible candidate to replace Gary Darnell as the head football coach at Western Michigan, where he had earned a master's degree and was an assistant football coach from 1984 to 1987.

In 2007, after serving as Eagles' special-teams coach for nine years, he became their defensive-backs coach. This fulfilled his request to head coach Reid and improved his chances of landing a head coaching job since executives at that time viewed special teams coaches as unqualified to move up to head coach.

On January 19, 2008, Harbaugh was appointed the third-ever head coach of the Baltimore Ravens after Jason Garrett, the team's first choice, decided to stay with the Dallas Cowboys after receiving a raise and a promotion to assistant head coach. He was not considered one of the favorites for the position because he had no head coaching experience at any level and had never been an offensive or defensive coordinator in the NFL. He impressed team owner Steve Bisciotti and Vice President of Player Personnel/General Manager Ozzie Newsome. New England Patriots head coach Bill Belichick also recommended Harbaugh to Bisciotti by phone during the interview process.