A cause of many or most of the bad happenings in a story, and often the main cause of most or all of them. A Big Bad could be a character with Evil Plans or it could be an omnipresent situation, such as a comet heading towards the Earth. In a …| TV Tropes
"MacGuffin" (a.k.a. McGuffin or maguffin) is a term for an object or element in a story that drives the plot, but serves no further purpose. It won't pop up again later, it won't explain the ending, and it won't do anything except possibly …| TV Tropes
Anton Chekhov, master of the short story, gave this advice: If it's not essential, don't include it in the story. The term has come to mean any object that later turns out to be important. For example, when a character finds a mysterious necklace …| TV Tropes