Hese are some ideas for the main antagonist in the series:

Cult leader: A mysterious high school student who goes to church every Sunday and was a very respectable guy. Until one day, when he saw Myers mocking and laughing at Cthulu's face, he snapped. He sends his followers to kill Ralph and his friends and bathe in his blood.

Vampire: He is a descendant of Vlad Țepeş/Dracula and he must find a way to gather more blood in order to survive, and what better way to find blood from no other than Ralph. He has fangs and night vision, making him capable of hunting during the night.

Slime monster disguised as a human: Another high school student who is down to earth and pays little to no attention to nobody. He lives with his family in extreme isolation, until he saw a black slimey thing crawling on his foot then entering his ear. It is called a Nergaling. His transformation made him a powerful and flexible villain that can phase through walls with ease.

Rich kid: He comes from a very wealthy family living on the beach. His arrogance, hissy fits and obssession of robots and electronic components make him a force to be reckoned with.

Masked serial killer: This is the story of Vincent, a sad disturbed teenage camper who had a very tragic past. Everyday at Camp Wawanakwa, he was often bullied and laughed at because of his scar on the left eye. One day, he's had enough; he put his mask on and started throwing rocks at them and yelled "I'll get my revenge on y'all mother******s! I'm going to ******* skin you all alive!", and Ralph shot him in the left eyeball, leaving him dead, after which he came back to life after everybody left. This is the reason why he turned into a psychopath now. He makes elaborate plans to kill people and executes them flawlessly. He goes on an ongoing rampage to find and exterminate Ralph and his friends for good.

Duncan: Duncan Tarun, labeled the delinquent, was originally a camper in Killer Bass. He is the ultimate bad boy, he causes trouble wherever he pleases. His distain towards Harold, Ralph and the other campers is caused when one day, Courtney, his only true love, went missing and started accusing them for kidnapping and taking her hostage. After he saw Gwen and Trent tie her up in an electric chair and interrogate her, he swore to avenge her and started a fistfight and started threatening Ralph Myers to murder him and use his skull as decoration, which ended with him being sent to juvies. He came back and is still looking for Courtney, only to wreack havoc upon the entire planet.

Cody: Cody Anderson, labeled as the geek, was also a camper who worked with the Screaming Gophers to win 1000000 dollars. Him being tech-savy and cool with everyone made him so popular with the ladies, especially Sierra. One day, he betrayed literally everyone who was his friend and decided to work on his plan to create a dystopian nightmate mech city, and this is where he suddenly became one of the most deplorable people on Earth. He also tortures his victims his his deadly devices and he admits that he enjoys it.

Note: he is german.