Clowns in horror

Clowns have been around since the 1800's as comic performers, performing in circuses performing in a physical/slapstick style, sometimes including mime.

Clowns became popular from "Comedia dell'arte" based off Greek and Roman characters as the "Rustic Fool". Court jesters and harlequin have references to the historic side of clowns.

Horror films like to twist different situations to make them horrible, such as making dolls scary, going into a forest or an old house etc. Because of this, the horror genre changed the comedic side of clowns to be unpleasant. There are some links between paedophilia, as clowns often work at parties with children, so horror films can play on this idea.

Clowns are very staged un-natural characters, so clowns may be seen as covering someone's personality through costume or acting, making them suspicious. There are many clown masks which have the same eerie mysterious effect.

When clowns perform, they have a physical slapstick style and way of moving. This is another reason why directors can associate clowns with violence, such as slasher films.