Biff, Cliff, and Riff, brothers and members of the ruthless "Tannen Crime Family".
The Tannen crime family, also known as the Tannen Mob, was an extension of the Tannen family in an alternate 1986. They were considered the fifth most dangerous crime family in California. Resulting from events that occurred in 1931 surrounding Kid Tannen, Biff Tannen was now supported by two brothers, Cliff and Riff Tannen. What normally would have been bullying on the part of Biff was transformed into a crime syndicate of beatings and scaring of residents out of Hill Valley. The family crippled George McFly, leaving him paralyzed and in a wheelchair, making his wife Lorraine distraught, while their children Dave and Linda fled. As their reign of terror continued, they made allies with other crime families, most notably the Sacramento Mob, of which J. J. Valenti gave them a personalized gun lighter as a gift.
Marty McFly returned to 1986 thinking things would be normal again, but only found the three Tannen siblings at his parent's house, ready to fight him. Marty fought them off temporarily, only to find himself at the end of Old Kid Tannen's pistol. Luckily, Doc pushed the DeLorean into the back of Kid's vehicle and saved Marty. The alternate timeline was presumably erased once Doc and Marty returned to 1931 and interfered with events favoring Kid Tannen's success.