Mistimed Revival

The flickering of eyelids and improvement of vital signs shown by an unconscious or comatose character immediately after a friend or relative has departed subsequent to declaring in their presence that they're about to go do something noble, stupid, dangerous, or some combination thereof.

This is the unfortunately-timed occurrences of Eye Awaken and/or Finger-Twitching Revival.

Anime

 * End of Evangelion gets versions of this. Asuka wakes up from her Convenient Coma just in time for one more Crowning Moment of Awesome before getting THE single most brutal death in the entire series. And then Shinji and his mother finally gets themselves together (it Makes Sense in Context), and go out to save his love interest, and finds Asuka's mech's EATEN remains. Yeah... bad timing all round.

Comic Books

 * This happens to Batman in The Dark Knight Returns. Fortunately, the only one in a position to notice was Clark Kent (the vital sign in question was the sound of Batman's heart restarting, after he'd been buried), and he kept mum.

Theatre

 * Older Than Steam: Juliet's revival in Shakespeare's Romeo and Juliet after Romeo kills himself.
 * The Baz Luhrmann movie William Shakespeares Romeo and Juliet takes it to frustrating extremes, with Juliet's eyes actually fluttering moments before Romeo takes the poison, and Juliet waking up completely just in time to watch Romeo die -- and for Romeo to see her revive, and realize what he's done.
 * In the opera by Charles Gounod, they sing a duet before he dies. A fairly long one.

Western Animation

 * In The Simpsons, when Lisa is lying unconscious, possibly dead, Homer tells her "Lisa, if you wake up, I'll buy you a pony". She immediately sits up, saying "New pony!". Homer tries to convince her she dreamed it.
 * Played straight in Beast Wars. Enraged after the apparent death of Blackarachnia, Silverbolt hunts down Tarantulus to avenge her. He nearly kills Tarantulus by impaling him, but is interrupted by Rampage. Cue the return of the new and improved Blackarachnia, who kicks Rampage's ass and then admonishes Silverbolt for being a noble tool.