Hill Valley, CA's meanest, baddest hombre, circa 1885, and ancestor of Biff Tannen in Back To The Future III (and played by Tom Wilson). Tannen's short temper and tendency to drool earned him the nickname "Mad Dog", a moniker which he despised. When a stranger by the name of Clint Eastwood called Tannen "Mad Dog," Tannen replied by lassoing him and trying to hang him at the still-under-construction court house. It is unknown exactly how many people Tannen has killed over the years because a newspaper editor printed an unfavorable article about Tannen in 1884, and Tannen shot him in revenge. Records regarding Tannen were no longer kept after this incident.

In August 1885 Tannen sought the services of a local blacksmith, Emmett Brown, to reshoe his horse. On September 1, 1885 the horse threw the shoe, causing Tannen to be thrown from his horse and to shatter a bottle of whiskey that he happened to be carrying. Tannen blamed Brown for the mishap and demanded $80 from him for the cost of the horse and the whiskey. When the blacksmith refused, Tannen threatened to kill him.

At the Hill Valley Town Festival on September 5, 1885 Tannen attempted to shoot Brown with a small derringer, however the aforementioned Eastwood tossed a pie plate at Tannen, causing him to misfire the gun. Tannen was thrown out of the festival by town marshall Strickland for the gunplay. As a result, Tannen gunned down Strickland the next morning, September 6, and later went on to rob the Pine City Bank stagecoach. Tannen also challenged Eastwood to a gunfight for the morning of September 7 ("8:00 AM," Eastwood said, "I do my killing after breakfast.").

Buford Tannen finally met his match when, at the gunfight, he threatened to shoot Eastwood's blacksmith friend, and instead Eastwood tricked with a strategicly placed piece of iron. He then kicked Tannen's gun from his hand and knocked the gunfighter out. Tannen landed in a cart of manure and was arrested shortly after for robbing the stagecoach.