Is the killer clown real?
Pennywise, the clown you are referring to, is not real.
Pennywise also isn't a real clown. From Stephen Kings 'It'
Pennywise The Dancing Clown is actually a pregnant women. It is a
malevolent entity that takes form of your greatest fear. Pennywise
prefers the shape of a male clown, because it attracts foolish
children that eventually become the monster's food.