What is the work?
Scooby-Doo on Zombie Island is a 1998 direct-to-video film based on the eponymous canine and his gang of friends who solve mysteries. The series was known for its typical formula: a town reports on a spooky phenomenon; the Mystery Gang investigate it (often with Shaggy and Scooby being bribed with Scooby Snacks); splitting up, getting the monster in a trap and unmasking them, blah, blah, blah. You get the picture.
But in this first in a series of DVDs? This time the monsters are real as demonstrated when the Mystery Gang is invited to New Orleans, Louisiana, to Moonscar Island where they are severely out of their habitat. Probably the darkest piece of Scooby-Doo media aside from Mystery Incorporated which was followed by a sequel in 2019 which we will not talk about.
Who is he?
Jacques, a ferryman who takes travelers to Moonscar Island. While he seems to be a friendly guy, he actually knew that <nowiki>Simone Lenoir and Lena Dupree housed a dark secret: hundreds of years ago, their colony was attacked by the infamous pirate Moonscar and led the colonists to get eaten by alligators. Lena and Simone then pray to their cat god for vengeance and slaughter all the pirates. However, they realized they unwittingly cursed themselves, so they would absorb people's life forces to prolong their immortality. The "zombies" are the "good guys" in this situation with trying to warn potential victims as a way of ensuring they escape the same fate.
As werecats, Jacques wanted in on the deal so he could become immortal. But due to the intervention of Scooby and Shaggy, the werecats ran out of time with the harvest moon. With their ritual thwarted, all three crumble into dust ergo freeing all their victims.
Mitigating factors? Freudian Excuse?
No. He knew that Simone and Lena were killing people but he wanted to be immortal. At the least with Simone and Lena it could be argued that they at the least started out wanting to avenge their fallen friends but were now resigned to stealing life force as a consequence of invoking their cat god. They did not intend on becoming cursed, but Jacques fully accepts the curse as long as it means he gets to live forever.
Heinous standard
So, Jacques does not have an exact number of victims, but he has lured people to the island for years judging by all the zombies the Mystery Gang encounters. He is fully complicit in the scheme to steal life forces from visitors so I find him equally accountable. He already had a pretty established pattern he replicates on the Gang for instance. It was not his first rodeo.
Of course, I personally view the film as a standalone set in its own continuity disassociated with the Nibiru Entity from Mystery Incorporated who is also extremely dark and kind of feels out-of-place in a typically family-friendly franchise.