Some clowns from horror movies are Pennywise from the 1980s TV series "It," based on Stephen King's bestselling novel, The Laugh from the 2008 slasher movie "Amusement," and the three killers from the 1980s movie "Clownhouse." TV Tropes has a list of evil clowns in various media.
Some people find the exaggerated makeup of clowns to be unsettling. The killer clown archetype became popular in horror in the 1980s. A possible inspiration is real-life serial killer John Wayne Gacy, who sometimes performed as a clown. Some examples of evil characters that are not strictly clowns, but have a very similar look, are the Joker from Batman and Spawn's Violator.