The Evil Clowns  are vampiric lamprey-like creatures disguised as clowns that devour victims when they laugh. A nest of five were captured by the Extreme Ghostbusters.
At some point in time, a nest of vampiric entities settled in Coney Island on the southern tip of Brooklyn. Dressed as clowns, they set out to feed on laughter. If unable to, they invoke it with their disguises.  At their choosing, they can also turn human victims into one of them.  An eyewitness saw one of the clowns feed on a man who missed a local bus and called the Ghostbusters for help. They tracked the clown to another victim's apartment room and fought it. At the time, Eduardo Rivera and Garrett Miller were competing with each other. Eduardo managed to confine and trap it himself. The Ghostbusters were unaware that the other three clowns were watching from afar. They decided to get revenge on Eduardo and targeted him as a replacement for their fallen comrade. While Eduardo was heading home, he was attacked by their jack-in-the-box emanation and bit.
The Ghostbusters then received a call to the comedy club, "Laugh Riot," at 23rd and Sheldon. The trio of clowns easily escaped capture but Eduardo's transformation began to progress. Egon Spengler discovered Eduardo's white blood cells were mutating.  Upon analyzing one of the clowns' gloves, trace amounts of beach sand, popcorn, and mustard were discovered. As the remaining Ghostbusters went to investigate Coney Island, Slimer mistakenly released Eduardo. Unable to invoke laughter from Egon, Eduardo traveled to Coney as a fully transformed clown entity. He feed on Roland Jackson and stalked Kylie Griffin and Garrett. They then trapped the other three clowns. Hopelessly overpowered by the head entity, Kylie and Garrett were saved when a laughing man in a trench-coat arrived out of nowhere. It was actually Slimer with a tape recorder. Kylie, Garrett, and Egon, armed with a Field Projector, trapped the entity. Eduardo was returned to normal and all victims were redistributed around the fair grounds, albeit naked. They all also had short term memory loss and had no recollection of their ordeal.
The first one resembled the usual appearance of a clown. The other three resembled a chicken, a clown resembling a knock-over toy dressed in black, and a massive, scary clown wearing boxing gloves and a tutu. The fifth one was their master, a giant lamprey creature hiding in a ticket booth shaped like a clown.
The weakness of the vampires is that they can't prey on someone unless they laugh first. To counter this, they use their clown disguises to try to bait them into laughing.
In addition, the giant leader of the clowns has several tentacles with tips covered in soft, feather-like appendages it uses to tickle victims into laughing.
What's worse is that they have the ability to infect other people using a special jack-in-the-box to turn them into vampire clowns too.
- A ghostly clown appeared as a boss in Extreme Ghostbusters: Code Ecto-1, but he lacks any resemblance to the lamprey-vampires.
- Kylie's analogy for the clowns are "Laughter Vampires."  The entities' true names are not revealed. On the official website, they were simply referred to as "Evil Clowns"
- ↑ Extreme Ghostbusters (archived) website - Ghostly Archives A-E
- ↑ Kylie Griffin (2009). Extreme Ghostbusters- Killjoys (1997) (DVD ts. 8:39-8:42). Sony Pictures Home Entertainment. Kylie says: "Bait. If it can't find laughter, it tried to invoke it."
- ↑ Egon Spengler (2009). Extreme Ghostbusters- Killjoys (1997) (DVD ts. 13:56-14:01). Sony Pictures Home Entertainment. Egon says: "A Vampire is known to either feed on a victim or turn the victim into one of their own, if they choose."
- ↑ Egon Spengler (2009). Extreme Ghostbusters- Killjoys (1997) (DVD ts. 13:45-13:48). Sony Pictures Home Entertainment. Egon says: "The white cells in Eduardo's blood are mutating. He is transforming."
- ↑ Kylie Griffin (2009). Extreme Ghostbusters- Killjoys (1997) (DVD ts. 12:27-12:32). Sony Pictures Home Entertainment. Kylie says: "It's an analogy. These clowns are Laughter Vampires. They feed off laughter instead of blood."