5. Clock Tower Woman – Back to the Future (1985)
Early on in Back to the Future, a woman interrupts Marty McFly as he’s attempting to put the moves on his high school sweetheart, but she also saves his life and enables the plot of both of the film’s sequels in the process.
Despite her brief screen time, her passion is unforgettable: she wants to save the Hill Valley clock tower, and she doesn’t care who she interrupts in the process. Rattling her tin in Marty’s face, she drops a little exposition about the lightning strike that broke the clock tower, then presses a flyer into his hand, which he stuffs into his pocket.
Later on, when he finds himself stuck in 1955 and in need of some serious power to get home, the flyer gives him the exact date and time that lightning will strike. This forms the basis of the plan which sees Marty return to 1985, and it was all made possible by Clock Tower Woman’s pestering.
Without the flyer, Marty likely would have known the date, but not the time of strike, making it impossible for him to channel the necessary power into the time machine. So, without the unnamed Clock Tower Woman, there wouldn’t be any Back to the Future Part II or III, and the film would have been called Stuck in the Past. If it hadn’t been for her, Marty would have been forced to reach 1985 the good old fashioned way: by waiting thirty years (and potentially witnessing his own birth).