An ABC timeline is when a time traveler goes back in time and commits an action that causes a drastic change to the present. That timeline is designated as [the present year][letter].
1985A was the timeline in which Old Biff Tannen stole the DeLorean in 2015 and gave a sports almanac to himself, telling him to bet on the winner so he will become rich. Biff followed his instructions. He eventually murdered George McFly in 1973 and married Lorraine Baines. In 1996, he was murdered by Lorraine as revenge for killing her husband and abusing her.
Doc goes back to 1938 to buy multiple copies of the original printing of the first issue of Action Comics. He sells them in 2015 or beyond, making himself a multi-millionaire. He then gets his DeLorean time machine hover converted and outfits it with a Mr. Fusion Home Energy Reactor.
Marty McFly, Jr. is set up by Griff Tannen for the robbery of the Hill Valley Payroll Substation. He is sentenced to fifteen years in prison. A week after her brother is imprisoned, Marlene McFly attempts to break him out and is sentenced to twenty years.
Marty poses as Marty Jr. and causes Griff and his gang to crash into the Hill Valley Courthouse, resulting in their being arrested, and as a result, the burglary never happened. In this timeline, Marty raced Douglas J. Needles in 1985 and crashed into a Rolls Royce, resulting in his hand being broken (leaving him unable to play the guitar again) and putting him in massive debt. As a result of his still being bullied by Needles, his 47-year-old self makes an illegal transaction using his CusCo credit card with the older Needles. Marty's boss, Ito T. Fujitsu, monitors the transaction, and sends him a fax informing him that he is fired.
The future of the chaotic 1985A. Biff does not exist in 2015Adue to either fading into future Biff-A or having been killed by Lorraine in 1996. Hilldale does not appear to have changed much from the 2015 timeline to the 2015A timeline, as shown by the scenes after Biff returns from his mission.
As a result of Marty not racing Needles in 1985, he doesn't crash into the Rolls-Royce. As a result, the text on the fax is erased, as Marty is no longer fired from his job at CusCo in this timeline.
Doc traveled forward and witnessed a nuclear holocaust in 2045. He sets up a video camera to record time being changed as it happens, and traveled to an unspecified point in time to prevent the holocaust from happening.
After Doc traveled to an unknown point in time, the hydrator, Nike MAG, hoverboard, hover conversions, and Mr. Fusion were no longer commercially available by 2015. This prevented the 2045 nuclear holocaust, but meant that most of the events that he witnessed in 2015B never happened.
A future reality where GriffTech no longer has destroyed the world via the usage of Mr. Fusion home generators. Furthermore, altering the original 2045 timeline has resulted in the disappearance of the Mr. Fusion, the hydrator, the hoverboard, and self-lacing sneakers.
- Back to the Future Part II
- Back to the Future: The Game
- Doc Brown Saves the World
- Back to the Future: Untold Tales and Alternate Timelines