Briefly, an episode or issue that suddenly focuses on a character specifically because they're going to die at the end (or fairly close to the end). Usually this is a relatively minor recurring character, or someone who technically is in the main cast but never had a Backstory or much in the way of characterization. The episode/issue may be honest about what's going to happen, or try to make it appear that the character is finally going to be promoted to a main character. Episodes about the death of a major character who already got plenty of exposure and a fairly full Backstory don't quite fit this trope, since it's not as obviously different from the character's normal treatment.