Why are so many people afraid of clowns?

I love clowns. Loooove them! Growing up, I had a collection of clown dolls, figurines, and toys, and I adored it. In high school I had a friend stay the night and she insisted I cover my collection with a sheet, or she would be unable to sleep. I knew people feared clowns, but never would've expected someone to cower in fear over a few dolls. 

So where does the fear of clowns come from? It turns out that our modern conception of clowns is just a snapshot in the mixed yet intriguing history of clowning. 

Clowns can be traced back as far as ancient Egypt, then Greece and Rome. They evolved into court jesters in the Middle Ages, and then a few star clowns started to make their mark on history. For example, Joseph Grimaldi and Jean-Gaspard Deburau shaped modern clowning on Europe in the 1800's. When Deburau caned a young boy to death in the street for taunting him, the legacy of the violent clown was born.

From Bozo the Clown to John Wayne Gacy, from street mimes to Saw, clowns do really just scare some of us to death, and maybe for good reason. 

The psychological theories about why children fear clowns but also respond very well to clown therapy are extremely interesting to me, but I don't want to go into all that here. Below are some links to additional reading if you're interested. 

http://en.m.wikipedia.org/wiki/Clown_Care

http://www.businessinsider.com/why-people-are-scared-of-clowns-2013-8

http://en.m.wikipedia.org/wiki/Coulrophobia