- "Shot in the back by Buford Tannen over a matter of eighty dollars? What kind of a future do you call that?!"
- —Doc Brown to Marty McFly about the tombstone
The tombstone was erected in memory by his love Clara Clayton who took care of him for two days while the bullet that entered Doc killed him slowly. After he died on September 7, he was placed in Boot Hill Cemetery, and the tombstone was engraved with "Erected in eternal memory by his beloved Clara".
It remained there for 70 years, ironically close to the DeLorean time machine he hid in the Delgado Mine, until Marty McFly and his 1955 self stumbled across it in horror. Marty took a photo of the tombstone and took it with him to 1885. On the night of the Hill Valley Festival where Doc was shot in the first timeline, Marty prevented it from occuring by intercepting the shot with a pie dish. The bullet that was shot only managed to hit the hat that Doc was wearing at the time and send it flying off of his head. This prompted Tannen to challenge Marty to a duel on Monday morning at 8:00 a.m.
From this point on, the inscription on the photograph began to vanish and the next morning, Doc theorized that it might have been "Clint Eastwood" on the tombstone instead with this change of circumstances. By the time of the duel, his alias appeared on the tombstone. Marty had then made the decision not to face Tannen. But he changed his mind only to save Doc who had been taken hostage by his gang. Tannen shot Marty down but Marty survived the gunshot by wearing a iron stove door on his chest. Marty then knocked Tannen headfirst into the tombstone (breaking it in half) before knocking Tannen into a cart of manure.
With Tannen defeated, and the tombstone destroyed, it vanished completely from the photograph before Marty's eyes.