The Killer Klowns were all portrayed by Steve Rockhold, Michael Harrington Burris, Geno Ponza, Scott Beatty, Paul Haley, Dennis C. Walsh, Genie Houdini, Charles Chiodo, Karl Shaeffer, Paul Parsons, Jimmy Locust, Mitch Bryan, and Greg Sykes.
Throughout the film, upon the sleepy American town of Cresent Cove, California on a Friday night they and their large circus tent-like spaceship underneath the guise of a glowing comet-like object, happened to landed in a nearby forest and began a gruesome "harvest" of humans though out the town via an array of wacky yet lethal devices such as ray guns that encase people in cotton candy (which kills people in cotton candy), shadow clown-puppets, acid pies, and other, even more other bizzare weapons and gadgets. In the early part of their rampage, one killer klown used a Tyrannosaurus shadow puppet that swallowed a group of humans and turned them into popcorn kernels and one of the small killer klowns used a cotton candy gun to trap a girl inside a cotton candy cocoon. They also kidnapped Debbie inside a balloon rather than trapping her in cotton candy or turning her into a popcorn kernel. Later on, 2 female Killer Klowns were seen, which explains that the male Killer Klowns are trapping human women inside balloons to turn them into the female Killer Klowns.
The Killer Klowns live up to their name and go on a mindless rampage of death and destruction until their weakness is finally exposed: their bulbous red noses - by hitting their noses, the Klowns are killed as and thus the main heroes of the film who are Mike Tobacco, Debbie Stone, Officer Dave Hanson, and the Terenzi Brothers started to fight back against the murderous invaders.
However, one of the heroes, Debbie Stone, is kidnapped by the Klowns and the reason behind their attacks is revealed in a disturbing scene in which she is taken aboard their "big top" space-ship that landed in a amusement park outside Cresent Cove as its second destination and witnesses them feeding on human blood via silly-straws.
Eventually, she is rescued by Mike and Officer Dave Hanson and the film climaxes in the ship's main room called "Klown Kathedral", surrounded by the Klowns, with a showdown between the heroes and Klownzilla - a 20ft tall Klown and leader of the Killer Klowns, despite his obvious advantage, Klownzilla is defeated when police Officer Hanson uses his police badge to burst the Klown's nose - which causes Klownzilla and the Klowns' space-ship which begins to coil in and spin like a top before lifting off the ground to leave Earth, to explode. Having escaped to the authorities who had gathered outside the amusement park, Mike and Debbie briefly mourn their friends' loss until the Klown's miniature car drops out of the sky. Dave is alive and they all embrace before Paul and Rich appear from the back of the car themselves, having hidden in the ice cream coolers to avoid the explosion. Debbie then asks if its over and pies fly down and hit them both in the face to the sound of the Klowns' laughter.
Miraculously, despite this the heroes manage to survive the explosion - it is unknown if there is an entire planet of Killer Klowns out there or if these were the only ones but it is safe to assume that these bizarre creatures will not be terrorizing Earth anytime soon following their defeat.
However, a sequel called "Return of the Killer Klowns From Outer Space in 3D" is set for a possible 2015 release, confirming their return.
The Killer Klowns
These Klowns have names, but never revealed in the movie, only in the Killer Klowns Wiki.