Martin Seamus "Marty" McFly is a fictional character and the main protagonist in the Back to the Future motion picture trilogy, played by actor Michael J. Fox in the three films and voiced by David Kaufman in the animated series.

Marty was born in 1968 in Hill Valley, California. He is the youngest of three children to George and Lorraine McFly. He has a brother Dave, sister Linda and girlfriend Jennifer Parker. His best friend is scientist Emmett Brown, who Marty (and Jennifer) calls "Doc." There is an impression that Marty is embarrassed by his family and does not spend much time at home, preferring to hang out with Doc, Jennifer, or the guys in his band, The Pinheads.

Marty is an easygoing adolescent most of the time. He is not the best student academically, but his grades are good, although he does have a tendency to be late for school. He plays lead guitar with The Pinheads and likes listening to Huey Lewis and the News, Tom Petty and the Heartbreakers, and Eddie Van Halen. He is a talented skateboarder.

Although often accident prone, when faced with danger, Marty is always brave and can be very resourceful and clever. His only major character flaw is his persistent desire to show others that he isn't a coward, which causes him to take unnecessary risks. He can't abide to being called 'chicken', a trait he shares with James Dean's character Jim Stark from Rebel Without a Cause (coincidentally made in 1955). However, by the end of Back to the Future Part III, Marty has realized he doesn't need to constantly prove his bravery and avoids one of the greatest tragedies in his life, a collision with a Rolls-Royce limo.