4. Shinzon - Star Trek: Nemesis (2002)
Shinzon, played by Tom Hardy, is a villainous clone of Captain Picard who vowed revenge on the Romulans who enslaved him and the Federation. Psychological depth and Picard's dark side are promised, but the execution is terrible. Shinzon is petulant and inept, not threatening.
Hardy is a brilliant performer (and future star), but the character is poorly defined, has no drive, and doesn't pose a threat. Shinzon's psychological attack on Counselor Troi makes him harder to watch. In Shinzon, the neglected orphan, Hardy found a "human soul."
This nuance doesn't work on screen, so we see a bald clone with a prosthetic nose having fits on the infamous Reman warbird Scimitar. Obviously, Nemesis didn't launch Hardy's career the way some may have predicted, and Shinzon made it the last and least successful TNG film.