Back to the Future star Michael J Fox has compared Donald Trump to franchise villain Biff Tannen.Biff – who Back to the Future writer Bob Gale previously confirmed was based on the then-property tycoon – is Fox’s character Marty McFly’s nemesis, and is known as an aggressive and selfish bully.Speaking in a new interview with The Guardian, the actor said of the US President: “Every worst instinct in mankind has been played on [by Trump], and for me that’s just anathema.