Maleficent. In Once Upon a Time, most major lore characters get entire episode long story arcs. In the final episode of Once Upon a Time, Maleficent is used as a hurdle between the show's main character and the episode's MacGuffin. She is introduced for the first time in the series, given a single line of dialogue, and killed within the span of 5 minutes.
Also, as a media guy, I'm surprised you're not watching the show. It's otherwise awesome.