She's fierce, polite, but will battle every guy in a mask. The beginning of the pop culture trope from the title started with Mari Collingwood in "The Last House on the Left" (1972). The phenomenon exists mainly in slasher films and refers to the main character, who is a female. It defines the last woman alive who is supposed to battle the serial killer and kill him. Often the final girl is a virgin. Always with excellent etiquette, she's also very friendly. A female character' trope introduced above is meant to survive everybody.