So long, SUCKERS!!!
~ Jacobo escaping from prison.
MYSTERY INCORPORATED! This is only the first rung on the ladder of your demise. And this time be the ones unmasked... as the buffoons you truly are!
~ Jonathan Jacobo as the Evil Masked Figure.
I would have gotten away with it... if it weren't for those meddling punks, and their dumb dog!
~ Jonathan Jacobo after his defeat.

Dr. Jonathan Jacobo is the main antagonist of Scooby-Doo 2: Monsters Unleashed.


Pterodactyl Ghost

Over the years Mystery Inc apparently caught him committing crimes dressed like a Pterodactyl Ghost.

Creating Life

Jacobo always wanted to create real monsters with a book.

Prison Escape

Years later, he broke out of jail on a hay glider to get revenge on them. He dressed up like a female reporter named Heather Jasper Howe and an Evil Masked Figure and turned his old Pterodactyl Ghost into a real monster with a machine he built, along with costumes of some other past Scooby-Doo monsters. They planned to get revenge on Scooby and his friends by destroying them and their hometown Coolsville. Luckily after a big battle with the Tar Monster, Scooby managed to turn the monsters Jacobo had created back into costumes.


Jacobo was unmasked twice before being sent to jail.


  • "So long, SUCKERS!!!"
  • "Help me, suckers!"


  • Jacobo's plan to get revenge on Scooby and his friends is similar to why Scooby's own Nephew Scrappy-Doo was the main villain of the first live-action Scooby-Doo movie (Monsters Unleashed is the sequel to that movie)
    • Both of them plotted revenge against Scooby and his friends after being wronged by them. (Scrappy because Fred kicked him out of the group for peeing on Daphne; Jonathan because they foiled his scheme.)
    • Both of them spend years plotting revenge and dressed up like people (Scrappy dressed up like Emile Mondavarious, Jonathan dressed up like Heather Jasper Howe)
    • Both of them had real monsters to do their bidding (Scrappy met a punch of purple demons, Jonathan turned classic fake Scooby-Doo Monsters into real monsters)
      • However while Scrappy might be remediable, perhaps in the long shelved third live-action big screen Scooby-Doo movie, Jacobo doesn't look very redeeming.
  • He was portrayed by Tim Blake Nelson who also plays Samuel Sterns/The Leader in The Incredible Hulk.