Buford "Mad Dog" Tannen is the main antagonist in Back To The Future Part III.
He was a local outlaw in Hill Valley, California in the year 1885. He was the son of Beauregard Tannen, the paternal grandfather of Irving "Kid" Tannen and Frank Tannen, the great-grandfather of Biff Tannen and the great-great-great grandfather of Griff Tannen.