Stephen King's IT terrorized millions in book form and then when it morphed into a 1990 TV miniseries starring Tim Curry in that iconic greasepaint which would traumatize a whole new generation into being coulrophobes.
Now Bill Skarsgard is playing the creepy shapeshifting clown that awakens whenever it has an appetite for the flesh of children (around every 27 years), some of whom come back as phantoms with their ghostly voices echoing through the sewers that are their graveyard. The suspense sucks you in to the point that you won't want to walk around at night because any door or drawer or cupboard could just burst open with a grinning clown face.
Turning on all the lights and not watching this in or anywhere near an abandoned basement is advised, unless you're really the sort of masochist who likes bolting up in bed at 3 a.m. screaming loud enough to scare the neighbors.
Just look at that cruelly painted smile and tell me this trailer isn't the ultimate nightmare fodder.