9. Tommy Jarvis Is The New Jason - Friday The 13th: A New Beginning
The fourth Friday the 13th movie, The Final Chapter, introduced a young boy by the name of Tommy Jarvis (Corey Feldman) who actually ends up "killing" Jason at the end of the movie by hacking him to pieces with a machete.
The ending also implies that Tommy has been traumatised by his encounter with Jason, a plot-line which carries through to the fifth film, A New Beginning, where a teenage Tommy (John Shepherd) has been institutionalised due to his PTSD.
When "Jason" returns, Tommy is the prime suspect for the killings, though he's eventually vindicated when the killer is revealed to be a Jason copycat.
However, the film's tantalising final scene sees Tommy wearing the Jason mask himself and raising his knife to attack Pam (Melanie Kinnaman) in a provocative cliffhanger which seemed to suggest that Tommy would become the new Jason.
But due to the overwhelmingly negative fan response to A New Beginning these plans were scrapped, and the sixth film, Jason Lives, effectively pretended this scene never happened, leaving fans to presume that it merely was a dream.
Instead, Jason Lives saw Tommy (Thom Mathews) accidentally resurrect the real Jason, and after defeating him yet again at the end of the movie, Tommy disappeared out of the franchise entirely with no further explanation.