Forest
Wing beasts (Bird, Owl, Sometimes eagle), land beasts (Wolf, Bear, Tigers, Moles), insect (Mosquito, Wasp, Spiders, Flies?), sometimes certain non-living lifeforms like Slime and Ghost/nocturne/spirit and possibly Mushrooms and certain other plant like species. Sometimes in rare cases, a living tree. And if someone really hates you, then Orcs and goblins should be in it as well. Bandits, are also common sometimes in a dreary woods.
EDIT: Lizard can be found in Forest as well.
If there's a presence of water in the area, certain kind of Turtles and Ducks should be thrown in if possible.
In rare cases, dragon-like creature are there.
If there's a presence of ruins, Golems, non living (skeletal), insects and material based like Rocks or possibly Sand worms. Goblins/Orcs should be presented there too.
If swamp, then should be poisonous creatures, spirits and possible swamp monsters? Possibly certain kind of beast, and nocturne creatures. There's some goblin/Orcs there, as well as some dragon-like creature.