In Jumanji, there are many dangerous characters. Most appear only once. The recurring characters include:

  • Van Pelt (voiced by Sherman Howard) - The big game hunter who wants to mount everyone's heads on his wall. He hunts everything, man or beast without remorse. He hates Alan and wants to kill him (referred to as Human hunting). His most commonly used word, if anything goes wrong, is "Blast!" He is killed by Peter in one episode, but Peter becomes him as there must always be a hunter, so Alan and Judy bring him back. He has poor communication skills.
  • J.H. "Trader" Slick (voiced by Tim Curry) - The wicked merchant of Jumanji, who sells items to anyone who can meet the terms of his transactions, and has been known to sell simple tools to rare and powerful artifacts to a vast clientele throughout the series. He lives and sells his wares at a trading post located at the heart of the jungle. He always says his whole name when introducing himself, but his middle name changes a lot of time. Some of the items he has sold include a rare paint he tricked Alan into buying, the Slickomatic, a giant potion to make Peter grow and later the antidote, the ChronoRepeater, a "Get Out of Jumanji Free" Card that only worked once, a love potion for Judy, and even a motorboat which allows Peter and Judy to return to their time. If necessary, he becomes a real danger to the trio, but his biggest part in the series is just a sly, cunning swindler a.k.a. "Honest John Dealership".
  • Professor J.S. Heinrich Ibsen (voiced by William Sanderson) - The mad scientist of Jumanji. He invents dangerous Steampunk-like machines. Ibsen is tasked to "work" for Jumanji, creating dangers and nightmare machines like poisoned acid-spitting frogs and battle-armored rhinos. He sends daily reports to "Jumanji" itself which broadcasts throughout the jungle. He calls himself a "Master Builder of Jumanji." This is a reference to the Norwegian playwright Henrik Ibsen and his play "The Master Builder".
  • Captain Ishmael Squint (voiced by Charles Napier) - The cruel pirate who sails the Jumanji Sea. In "Eye of the Sea", he lost his nose during the battle against the one-eyed sea monster with a hideous odor called "The Draken" over 20 years ago. The Draken is something of a cross between a dragon and a kraken, with a single huge eye. Squint's vengeful pursuit of the Draken is remininscent of Captain Ahab in Moby Dick. The monster ate Squint alive before Alan stabbed it in the eye, killing it. In "Return of Squint", he later came back with two new shipmates. He forces Judy, Peter and Alan to help him search for treasure at the bottom of the sea with Ibsen's submarine, but get captured by demonic mermaids with his new shipmates while the other three escape.
    • Mr. Shreve - Squint’s 1st one-eyed shipmate.
    • Mr. Shatic - Squint’s 2nd one-legged shipmate.
  • Stalker (voiced by Richard Allen) - The demonic Grim Reaper villain who is the Protector of Jumanji. He's the "Game Over Demon" of Jumanji. He first appeared in "No Dice" when Alan stole the dice from the real world. He is apparently destroyed when he is crushed by a piston, but is revealed to have survived. In "The Gift", Stalker brought Van Pelt, Trader Slick, and Professor Ibsen together to kill the kids after Alan was poisoned by a demonic centipede as Peter threatened to destroy Jumanji if Alan died. He is again defeated after being shoved down a waterfall by Alan, but survives again. His name and destiny was never revealed in the show.
  • Aston Philips (voiced by Dabney Coleman) - The greedy adventurer. He considers himself the biggest and bravest and betrays even his agents: Alan, Judy and Peter. His catchphrase is "Aston Philips has done it again". Though he was thought to have died in the Temple of Riddles in "The Palace of Clues," he actually survived and resurfaced when it came to looking for the Golden Goblet of Jumanjicon. He encountered Alan, Judy, and Peter again in their search for the artifact and even reclaimed his compass that Trader Slick swindled him into trading. After drinking from the Golden Goblet of Jumanjicon, he reverted to childhood form.
  • Ludwig Von Richtor (voiced by Alan Oppenheimer) - The German hunter who is the rival of Hunter Van Pelt. He competed with Van Pelt in hunting Alan. In "The Ultimate Weapon," Ludwig Von Richtor was present at Trader Slick's auction for the Trans-Vector of Jumanji.
  • Judge (voiced by Edward Asner) - An ape-like law keeper that presided over the trial of Alan when he was accused of stealing the Singing Orb from an ape. However, he is not a benevolent Judge as he condemns all without regard to innocence. He is also very greedy as shown when he takes an orb from the Fludgels and is sucked into it. In "The Ultimate Weapon," the Judge was present at Trader Slick's auction for the Trans-Vector of Jumanji. His only weapon is "Justice" which is a giant gorilla.
  • Flint (voiced by Charlie Schlatter) - An evil wizard created by Jumanji to mess with Judy's mind. Turns people into stone, but is defeated by Judy when she reflects his own attack back at him, freeing his victims and turning him to stone. Is presumably destroyed when his statue falls thousands of feet to the ground.
  • Jamazon Queen Gina - The leader of the Jumanji Amazons. Tries to marry Alan, but is defeated by Aunt Nora. In "The Ultimate Weapon," Queen Gina was present at Trader Slick's auction for the Trans-Vector of Jumanji but did not take part in the reclaiming of the device.
  • Black Ant Queen - The Black Ant leader of Jumanji. In "The Ultimate Weapon," the Black Ant Queen was present at Trader Slick's auction for the Trans-Vector of Jumanji but did not take part in the reclaiming of the device.
  • Red Ant Queen - The Red Ant leader of Jumanji. In "The Ultimate Weapon," the Red Ant Queen was present at Trader Slick's auction for the Trans-Vector of Jumanji but did not take part in the reclaiming of the device.
  • Sand King (voiced by Jim Cummings) - The sand monster who is the ruler the sand kingdom and tries to get a chest of cursed gold from Judy, Peter and Alan. He gets destroyed by Peter with a squirt gun.
  • Mud Boy(voiced by Dee Bradley Baker) - A mud boy that comes to life from a drawing Peter made in the mud, he starts out friendly but Judy tells him off which makes him mad.
  • The Narrator The supposed master of Jumanji whatever he writes down happens in Jumanji, he has been monitoring Peter et al until Love on the Rocks where they meet him in person. The Narrator reveals that he is actually a young boy called Oscar and is actually benign albeit very silly and likes to muck about.
  • Oscar The Narrator's true identity, he isn't truly a villain as he joins forces with Peter and Judy but he's very silly, even more so than Mud Boy as such his antics annoy Peter or get him in trouble. Oscar likes clowns, big shiny noses like Screwy Squirrel's or a clown's nose for that matter, mud and slime and other gross stuff, candy and turning himself and others into babies. It's later revealed he isn't the master of Jumanji, he works for it just as all the other residents do but he betrays Jumanji in Gift to travel with Peter and Judy on their adventures.