Born on October 2, 1958, Weissman first worked for Robert Zemeckis and Bob Gale in their film I Wanna Hold Your Hand, where he appeared, without on-screen credit, as a fan of Ringo Starr. Bearing little resemblance to Crispin Glover, Weissman received heavy makeup and facial prosthetics in order to portray George McFly, then was filmed hanging upside-down in an anti-gravity Ortho-lev in the McFly residence in 2015. Weissman also imitated Glover's voice in portraying George. However, he was not well received by the cast, who barely even bothered to learn his name, as Lea Thompson, for example, referred to him as "the guy playing Crispin". Subsequently, Glover filed a lawsuit against Universal for unauthorized use of his likeness, as well as their having reused footage of him from Back to the Future without either his permission or his receiving any payment. A settlement resulted in a change in the rules of the Screen Actors Guild (SAG) to prohibit its members from unauthorized mimicking of other SAG members.
Interestingly, George McFly is not the only person portrayed by both Jeffrey Weissman and Crispin Glover. In the 1991 film The Doors, Glover played the role of artist Andy Warhol. Weissman played the role of Andy Warhol in a 2000 television movie, The 70s. Jeffrey was born in Santa Monica, California, the fourth child to Dr. Wallace and Kate Weissman. Jeffrey's father, nicknamed Wally, is a retired psychotherapist and counselor
Jeffrey was also cast in Clint Eastwood's return to westerns, Pale Rider when actor Chris Penn, originally cast as Eddy Conway wanted a meaner role of a bad guy, and Clint moved him from the role of Eddy Conway to the role of Josh LaHood. Chuck LaFont, originally set to play Teddy, was then moved to play Eddy Conway, and Jeffrey took over as Teddy Conway.
Weissman married his Junior High School sweetheart, the former Kimball Jackson on April 10, 2004. after courting for nine years. They have two children, sons Spencer and Nicholas, and they reside in Hollywood. In 1995, they reunited after they had dated for a year in 1972-73 when they worked together in Children's Theater while attending Junior High School together in Santa Monica.