Any talking head that makes a living spreading hysteria. CNN, Fox News, and the like harbor them.
Sean Hannity, Don Lemon, Bill O'Riley, Wolf Blitzer, Bret Baier, Rachel Maddow, Van Jones, and so on.
The asshole hysteria merchants on Fox and CNN want to keep everybody in a state of fear with the relentless bullshit
they sell to the mindless idiots who worship them.
When fake or sensational videos are uploaded to YouTube and propelled by alarmist users into the mind of the general population, spawning urban myths, group-think, or panic.
"Dude did you hear that there is a hidden camera in your cable box watching you jerkoff?"
An overwhelming and practical response from the fans to events in a TV series, book, film, etc.
The first nine hysterical women were Torchwood fans, who sent coffee and letters to the BBC protesting against the death of Ianto Jones. Over 900 people registered on one LiveJournal community alone.
Russell T Davies: "The 'controversy' over Ianto's death is just nine hysterical women."
Or:
If (character) dies this series, they'll have nine hysterical women on their hands.
A disproportional emotional over-reaction to a crisis (or event) caused by an overstimulation of the limbic system that renders efficient function of the pre-frontal cortex extremely difficult.
Bystander #1: "Excuse me... why are they yelling and screaming like that? Are they OK?"
Bystander #2: "They have Hispanicus Hystericus. They'll be OK as soon as they calm down."
When the populace's fear of a snowstorm creates traffic jams and general panic way before any flakes even fall. Usually turns out to be a totally disproportionate response to a minor snowstorm.
Everyone is fleeing the office thanks to snow hysteria...but it isn't supposed to start snowing until 9 PM.