- "Hey, dollface, it's past time for our three-thirty!"
- —Irving "Kid" Tannen" to Edna Strickland Tannen
Kid Tannen ran a speakeasy business that was destroyed in an explosion in May or June of 1931. Upon learning of the "news" that Emmett Brown was responsible, he shot and killed Doc in a barrage of gunfire. When Marty McFly intervened, history had altered to that Tannen would take Doc out of the Hill Valley Police Station and then kill him somewhere out of town. That plan was foiled when Marty rescued Doc with the drill machine that he and Doc's younger self constructed, forcing him to crash into a manure truck.
Two months later, Tannen opened his underground speakeasy, El Kid, beneath the Sisters of Mercy Soup Kitchen. His girlfriend, Trixie Trotter would sing on the stage in the speakeasy, with Cue Ball at the piano, Matches guarding the door, Zane working the bar, and a croupier running gambling. Business was smooth, until the reappearance of Marty in disguise as a gang member of the Sacramento Mob. Matches came to Kid with a stick of dynamite that he had found along with many others around the speakeasy. Kid opened a secret passageway by turning the knob of the roulette wheel. Marty under his alias convinced Trixie to turn on Tannen by revealing unpaid taxes in records, that she in turn handed to Officer Danny Parker. Parker made arrests of Kid's accomplices, but not before Kid located the individual who had been burning down speakeasies: Edna Strickland. The situation quickly turned heated, with Kid revealing a Tommy gun and opening fire on both Marty and Officer Parker.
Kid Tannen would be imprisoned for several years, but broke out in 1937 for three hours, in which he made love to an unnamed woman, before being arrested again. How long Kid's overall imprisonment was is not mentioned. However, it is likely that Kid was in jail until at least as late as November 1955, as Biff is shown to be living with his grandmother Gertrude Tannen at the time. The identity and fate of Biff's mother is as yet unrevealed, but she apparently was not in the picture anymore as of 1955, either by death or leaving Kid and Hill Valley.
In an alternate timeline where Tannen was not arrested in 1931, his family expands as the Tannen Mob. In this reality, his three sons, Biff, Cliff, and Riff Tannen work for him by inflicting pain on residents of Hill Valley that refused to pay up. Just as vicious as ever, possibly even more so, he appeared in a car outside of Marty's house with his pistol Kid Jr., intending on killing Marty. However, his vehicle was rear-ended by the DeLorean time machine, which took off into the sky, foiling his plans. Marty and Doc returned to 1931 and convinced Trixie to testify against Kid. Although they their efforts succeeded in negating the 1986A timeline, they inadvertently created the dystopian 1986B timeline. Kid's fate in 1986B is unknown.
In the newest timeline, Kid Tannen shared a cell with Edna Strickland, who had been arrested on October 13, 1931 for burning down his first speakeasy. Although he had tried to kill her only two months earlier, they eventually fell in love and got married, although Edna was not Biff's biological mother. In the new 1986, he has seemingly given up his criminal acts and has a more upbeat attitude, presumably as a result of Edna's more ethical influence.
- Kid takes many influences from the Prohibition era gangster Al Capone. Such cases being running a speakeasy, running a soup kitchen and later getting arrested for tax evasion.
- Back to the Future: The Game