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 20 ft 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 release in 2013, confirming their return.
The Killer Klowns
These Klowns have names, but never revealed in the movie, only in the Killer Klowns Wiki.
- Jumbo, one of the main Klowns, who liked to annoy Curtis Mooney before killing him and making him his ventriloquist puppet.
- Fatso, a fat Klown who looks like Chubby. Killed a woman who he gave a Valentine's Day card to.
- Shorty, one of the main Klowns. He is the shortest Klown who in 1 scene punched off a gangster's head for breaking his bike with boxing gloves.
- Rudy, one of the main Klowns. He was the first to detect Mike and Debbie's presence at the Klowns' tent and went on a store raid to collect items, terrifying Mr. Myers the store owner.
- Spikey, one of the most commonly-seen Klowns. He in 1 scene did a puppet show for someone before killing him. Spikey also can make a balloon hound that acts like a prison hound.
- Slim, one of the main Klowns. He uses the Tyrannosaur shadow puppet to kill hundreds of people, pretends to drive a motorcycle to push a driver in a car off a cliff, jumps up an extremely tall height, and kidnapped Debbie inside a yellow balloon.
- Bibbo, one of the most commonly-seen Klowns. He has a yellow Mohawk and yellow-red suit.
- Chubby, one of the main Klowns. He demonstrated that the Klowns' purpose in killing humans is to drink their blood using crazy straws.
- Joe, a surveillance guard of the Parade Klowns.
- Magori, only has a small cameo whacking Mike and Debbie while his face is printed on the posters.
- Talls, a surveillance guard of the Parade Klowns.
- Storefront, a surveillance guard of the Parade Klowns.
- Frank, one of the klowns who appeared with the klown army to whack down Mike ,Debbie, and Officer Hansen. He has yellow afro hair with a bald spot and wears a blue suit with pink stripes.
- Boco, one of the klowns who appeared in the middle with Joe and Chubby's second brother to whack down Mike, Debbie, & Officef Dave Hansen. He has yellow afro hair and wears a violet suit with pink stripes
- Female Killer Klowns (Rosebud and Daisy), who (off-screen) sexually harassed the Terenzi Brothers while Mike and Dave were looking for Debbie.
- Baby Killer Klowns, long-necked newborns who grow from popcorn. They were planted around by Jumbo.
- Klownzilla (Originally known as "Jojo"), the biggest Klown whose size makes the other Klowns clear a path for him to go after Mike, Debbie and Dave.