Stephen King’s It is generally considered the standard for the “scary clown” in horror movies, but there are so many other great ones! Here are my faves.
Stitches (2012)

(Stitches had quite the attitude, even before he died)
Highlights:
- killer clown origin story
- intestine balloon animals
- pretty much the most clown-themed deaths of any movie I’ve seen except Killer Klowns from Outer Space*
- or at least, the most punny deaths
- Stitches’ potty mouth
Killjoy (2000)

(Killjoy the clown, apparently shooting someone with bullets from his mouth)
This gem was an extra in the Puppetmaster collection DVD. I’m not sure I’ve ever seen an American horror movie with zero white people in it. The highlights:
- “Biiiiiiiiiitch”
- Why won’t the hot girl give the nerdy guy the time of day? Maybe because all he has is “Killjoy [his clown doll] and dark magic”?
- The so-bad-it’s-good effect – pretty hilarious if you’ve had a few drinks (can’t say the same for the sequels, though…)
Clownhouse (1989)

(Cheezo the clown’s come-hither look, and this was before an escaped mental patient stole his costume)
- a young Sam Rockwell acting like a complete asshole
- I know what I like to do is make out with my boyfriend at a family circus
- clown unibrown (clownibrow?)
Clown (2015)

(That wig is his hair now…)
- creepiest/dirtiest clown costume (actually a demon skin, but whatevs…)
- feeling dirty after watching it
The Last Circus (2010)

(The Sad Clown gets his revenge)
This Spanish film earns a spot on my list largely because it’s the one circus movie with a death by aerial silks! Highlights:
- clown makeup applied by an iron
- feuding clowns
- lots of actual circus performing
In my opinion, a good evil clown horror movie should have a least a little humor – after all, aren’t clowns meant to make us laugh? And while scary clown make up is, well, scary, I think it’s better for the clown to start out looking like all the other innocent clowns, and then grow more evil-looking – because clowns really aren’t meant to scare people!
*I personally didn’t like Killer Klowns from Outer Space, mostly because the clowns looked too fake for me (they were aliens, but come on). But there is death by cotton candy, so you might find it worth watching.