1977 is a year in the 20th century.
- Date Unknown: In either 1976 or 1977, 8-year-old Marty McFly sets the living room rug on fire. (Marty was 8 years old at the beginning of 1977, and turned 9 later in the year.)
- Wednesday, May 25: Darth Vader appeared on screen for the first time in the film Star Wars. It is unknown whether George McFly saw the film; or, if he saw the film in the altered Timeline 2, whether he recognized the name of Darth Vader as something that he had heard more than 20 years earlier.
- Sunday, September 11: The Atari 2600 was released.