The Back to the Future film trilogy and subsequent animated series feature characters created by Robert Zemeckis and Bob Gale.
The lead character of the series is Marty McFly. During the course of the trilogy, he travels through time using a DeLorean time machine invented by his friend Emmett Brown and encounters the villain, Biff Tannen, in several different time periods and visits his family ancestors and descendants.
Martin Seamus "Marty" McFly (portrayed by Michael J. Fox in the films and voiced by David Kaufman in the animated series and AJ LoCascio in Back to the Future: The Game) is the son of George McFly and Lorraine Baines McFly. Marty travels between the past and the future, encountering his ancestors and descendants. Marty and his friend Doc Brown help restore the space-time continuum while encountering Biff Tannen (or members of the Tannen clan) at various points in time.
Doctor Emmett Lathrop "Doc" Brown (portrayed by Christopher Lloyd in the films and Back to the Future: The Game, and voiced by Dan Castellaneta in the animated series) is the inventor of the DeLorean time machine. At various points in time, Doc helps Marty restore the space-time continuum and reverse the changes that were caused by time travel.
In 2008, the character was selected by film magazine Empire as one of The 100 Greatest Movie Characters of All Time, ranking at #76.
Biff Howard Tannen (portrayed by Thomas F. Wilson in the films and animated series and voiced by Kid Beyond in Back to the Future: The Game) is the main antagonist of the first 2 films and a local bully who harassed George McFly and has once altered history in the second film. He comes from a long line of bullies in Hill Valley, most of whom harassed members of the McFly family. Biff is also a descendant of Buford Tannen (also portrayed by Wilson), who is one of Hill Valley's outlaws during the 1880s.