Classic Fantasy is a Mythras supplement for dungeoneering in the percentile world. Here are some of the monsters (some of them classics we grew to love in the early days of RPGs) in the Mythras Encounter Generator format.
- Giant Killer Frog
- Poisonous Giant Frog
- Gorgon Lesser
- Hell Hound
- Nightmare Horse Demon
There are also some encounters adapted from the evocative Blood Tide supplement for pirate campaigns.
For the fun of it here is an undead variety of the crocodile of the Pamaltelan continent.
You will likely find more useful encounters with the Encounter Generator. There are users guides to finding encounters and creating encounters and monsters