Deep Blue Sea False or Decoy protagonist

When people saw this in the theater, they laughed, cheered, and clapped. This was the moment after Samuel Jackson's rousing speech when people were supposed to come together and work out a solution to a problem.  Even the score and camera pretend this was that heroic moment.  As we zoom in, the shark shows up right on cue to dash our hopes.  Even the characters in the scene are destroyed by the misdirection.  Brilliant.  

That shark read the script and waited for the right moment to make its own reshoots.  

There is a growing trend of movies setting up heroes only for the movie to knock them down for greater impact.  So, what is this trope?

One of the famous tropes, of recent times, is the guy or girl we believe is the hero, but ends up dying midway through the story.  This subverts the hero we’re supposed to cheer for.  One of the best examples of this trope is Samuel Jackson making that heroic speech in Deep Blue Sea.  

Looking through the TV tropes, one can see that it is either the decoy or the false protagonist.  

From the wiki, ((In fiction, a false protagonist is a literary technique, often used to make the plot more jarring or more memorable by fooling the audience's preconceptions, that constructs a character who the audience assumes is the protagonist but is later revealed not to be.))

Scream is another movie with this trope.  Drew Barrymore was promoted as the main character in the movie only to be killed in the first ten minutes, They snatched her away from us.  Remember, Barrymore was on the movie cover and promoted it as if she was the main character.  

Metal Gear Solid 2 is another story where the game misdirects us that we're going to be playing as Snake the whole time. Nope, we only play him in the first chapter.

The other story I remember this happening was in the delightful Cabin in the Woods. Remember, Chris Hemsworth has the moment when he was supposed to "get help" only to die senselessly...by accident.