The killing off of a character is a device in fiction, whereby a character dies, but the story continues. The term, frequently applied to television, film, video game, literature, anime, manga and chronological series, often denotes an untimely or unexpected death motivated by factors beyond the storyline, often done for emotional effect and to advance through the story.

In productions featuring actors, the unwillingness or inability of an actor to continue with the production for financial or other reasons (including illness, death, unavailability, or producers' unwillingness to retain an actor) may lead to that character being "killed off" or phased out from the storyline in another way, which ends their story arc. In some cases, they may or may not be mentioned at all.

"The Final Problem", an 1893 story by Arthur Conan Doyle, ends with Sherlock Holmes plunging to his death at the Reichenbach Falls, in struggle with his arch enemy Professor Moriarty. There is ample evidence that Doyle fully intended this to be Holmes' definite and final end. Doyle wanted to write no more Sherlock Holmes stories, feeling that they were distracting him from more serious literary efforts and that "killing off" Holmes was the only way of getting his career back on track. "I must save my mind for better things," he wrote to his mother, "even if it means I must bury my pocketbook with him." Conan Doyle sought to sweeten the pill by letting Holmes go in a blaze of glory, having him rid the world of a criminal so powerful and dangerous that any further task would be trivial in comparison; indeed, Holmes says as much in the story. However, the Holmes fans refused to be mollified, continually protesting and pressuring Doyle until he brought their hero back to life.

Doyle did permanently kill off Mary Morstan, who happily married Doctor Watson at the end of The Sign of Four, but who apparently became inconvenient for later Sherlock Holmes stories. Her death – never described directly, but only mentioned in passing in The Adventure of the Norwood Builder – allowed Watson to resume living with Holmes on Baker Street and set off with him for a new adventure at a moment's notice. Fans did not protest her end, and Doyle never brought her back.

Alexander Dumas wrote The Three Musketeers which proved highly successful, and added several sequels. However, the final one, The Vicomte of Bragelonne: Ten Years Later, ends with the death of all the Musketeers, one by one – making clear to readers that he would write no more of them.

In 1956, Ian Fleming was becoming disenchanted with his James Bond books and wrote to his friend, the American author Raymond Chandler: "My muse is in a very bad way ... I am getting fed up with Bond and it has been very difficult to make him go through his tawdry tricks." In April 1956, Fleming re-wrote the final chapter of From Russia, with Love, to make the book end with Rosa Klebb poisoning Bond and him falling unconscious to the floor - which allowed Fleming, had he wanted to, to announce that that was Bond's end and that there would be no further Bond books. However, Fleming later changed his mind; in the beginning of Dr. No it is recounted that Bond recovered from the poisoning, and he went on to many more adventures.

Science fiction writer Harry Turtledove has produced many series of alternative history depicting alternate versions of various wars (the American Civil War, The First and Second World Wars, the Korean War etc.). Such Turtledove books typically include a large cast of alternating point of view characters, drawn from both sides of the conflict, whose lives continually interweave with each other in the book's plot. In such books, Turtledove is in the frequent habit of suddenly killing off one or more of his characters, often a sympathetic one to whom readers were attracted. In some of these cases, a soldier character is depicted as getting unscathed through very heavy fighting and then getting killed in a trivial skirmish or incident – which does happen in real war but rarely in fictional depictions.

Because of the episodic format of television shows, audience feedback and approval is often a factor in whether or not a character is killed off. Damon Lindelof, executive producer of Lost, has been quoted as saying that despite the widespread hate for Nikki and Paulo, "We had a plan when we introduced them, and we didn't get to fully execute that plan. But when the plan is executed, [they] will be iconic characters on the show." In an example of a character being killed off as a result of an actor leaving the show, Raymond Cruz's character Tuco Salamanca on Breaking Bad was killed off because he found the part too difficult to play. Characters may be killed off when the actors die, while in some cases the death of an actor results in a new actor being selected to take over the role. John Ritter's character in 8 Simple Rules was written to have died off screen after Ritter himself died during taping of the show.