Fandomentalist
A member of a fandom who engages in extremely toxic behaviors most commonly associated with religious fundamentalism, especially overtly hostile and abusive treatment toward non-members and other fandom subgroups, targeting specific individuals for coordinated harassment and bullying in retaliation for perceived slights, and aggressively dogmatic attitudes about fandom canon.
Once the fandomentalists had made up their minds that she was to blame for writing they did not like in a television show, they refused to accept that she was not at all involved with the show.