Main Killers:
* Jason Voorhees (Various Actors): The iconic slasher. Initially a victim of camp negligence, he returns as a vengeful undead force, hunting campers across multiple films. His appearance changes across the series as he evolves from a deformed child to a hulking monster.
Other Killers:
* Pamela Voorhees (Betsy Palmer): Jason's mother, driven mad by grief and vengeance after Jason's death, is the primary antagonist in the first film, hunting down the camp counselors.
* Roy Burns (Christopher Nelson): The killer in Friday the 13th: The Final Chapter. He is a deranged, machete-wielding man who impersonates Jason.
* Tommy Jarvis (Tom Savini): The character who confronts and kills Jason in "The Final Chapter" but eventually becomes the main antagonist in "Jason Lives." He's a complex character who often fights Jason.
Important Note: The Friday the 13th franchise has a complicated continuity, with several films retconning previous entries. This breakdown focuses on the most prominent killers, and there are various other antagonists throughout the series, such as the killer in "Jason X" (a cloned Jason in space).
Let me know if you'd like more details about a particular killer or want to discuss specific film plots.