The Three-Headed Monkey is a creature of legend that appears rarely in the series and is mentioned far more often. Most commonly, Guybrush will use the line "Look! It's a three-headed monkey!" to try to distract people, with varying success.

The Zombie Yeti is the last zombie that the player will encounter, as its first appearance is either Dark Stormy Night (level 4-10, the second time Adventure Mode is played) or a mini-game. The Zombie Yeti is based on the cryptid Abominable Snowman (Aka: Yeti) that lives in the Himalayas.

Hidden Runner is a dark and light green and blue Troodon. Voiced by Rob Paulsen (TV series). The only appearance, so far, as been in the tv series Episode The Spooky Nighttime Adventure. He has the ability to blend in with it's habitat due to it's multi-colored markings, giving the impression that it can turn invisible.

The unnatural, abominational horror that is Painis VagiCake is the result of secret genetic experimentation on GMod Monsters. A group of scientists took samples of DNA from Painis Cupcake, Vagineer, and Weaselcake to an underground base, and used a special catalyst to fuse the three materials together.

When Scooby-Doo and Shaggy Rogers were fighting over the "last" Scooby Snack, the snack almost fell into a crack and a Jackalope appeared and sniffed it and the two thought those animals weren't real. It took the last Scooby Snack and ate it. The two ran after it for taking the last snack, but it ran into a dark cave, but the two didn't follow.

Baby dragons are the highest level Summoning pet, requiring level 99 Summoning to obtain (although TzRek-Jad has the same summoning requirement, plus an additional requirement of 99 slayer.) A baby dragon may be obtained by hatching a dragon egg, dropped by all adult chromatic dragons.

This upgrade is unlocked after buying and placing fifty Portable Lakes. It activates the ability "Sea Monster Activate!", temporarily popping five layers of bloons with its tentacle. The tentacle can lash out five times before returning to normal pool state. The tentacle seems to have unlimited popping power.

The Ghosts of Halo are unidentified and/or players that tend to spawn out of nowhere during Multiplayer games, exclusively sighted in Halo 2, Halo 3, and Halo: Reach. Such ghosts tend to behave bizarrely and possess odd features. Among other things, they lack gamertags, do not show up on the scoreboard, and move erratically. They can be hostile if provoked, though some have been known to attack actual players for no reason. On some occasions, they are also invulnerable and will not die.

Nosey is a sea-monster that lives in Lake Nose. Nosey is similar in appearance to a plesiosaur, the Loch Ness Monster, and most closely resembles a cryptoclidus with plates along its spine.

In Generations I and III, the ghost of a female Marowak haunts the Pokémon Tower in Lavender Town. It died at Team Rocket's hands.

The Abominable Snow Mollusk is a huge monster that appeared in the special episode Frozen Face Off. Unlike other monsters shown, it is animated with stop-motion.