18. John 'Khan' Harrison
Look, Benedict Cumberbatch was great in Star Trek Into Darkness. His gravelly voice and cool demeanour was everything that a good villain needed - just not this villain. Insisting on making Into Darkness a remake of the Wrath of Khan was the film's undoing, as it left the performance up for instant comparison.
The idea of recasting itself is hardly an issue. Both Chris Pine and Zachary Quinto were fantastic as the new Kirk and Spock respectively. Yet recasting Ricardo Montalban with Cumberbatch was a poor choice. The first option, Benicio del Toro, may have been a wiser option, even if it didn't work out.
The reveal of the character's true name was a damp squib. The music swells and the camera closes in on Khan's face as he identifies himself, though it has been much parodied since. There was no reason for his Khan to expect any reaction from Kirk and Spock, as these versions have never heard of him.
Finally, he switches from a sympathetic villain fighting to save his crew and family to an out-and-out nutcase in the final act, before being put in stasis and left to rot. Unfortunately, this was one of the low moments of the rebooted series.