Void-Tyrannosaurs - Tall bipedal creatures with anatomy similar to prehistoric tyrannosaurs. Their scales are black with pulsating veins of purple occasionally streaking through them
Void-Raptors - Short bipedal creatures with anatomy similar to prehistoric velociraptors. Their scales are black and pulsating veins of red occasionally streak through them
Void-Dactyls - Large flying creatures with anatomy similar to prehistoric terrasaurs. Their feathers are black, their wings are also black laced with deep blue pulsing veins
Void-Ceratopsids - Large quadrupedal creatures with anatomy similar to prehistoric ceratopsians. Their scales are black with pulsating veins of deep green
Void-Stegosaurs - Large quadrupedal creatures with anatomy similar to prehistoric stegosaurians. Their scales are black and their plates/spines are golden
Saurians - A primitive race of sewer dwelling mutants closely resembling lizard people. The fight against other sewer creatures and occasionally set up colonies by chiseling into the stone. Their weapons range from their claws to spears and axes made from the bones of their victims.
Bovids - A primitive race of plains dwelling mutants closely resembling cow people. They are peaceful towards vegetarians, but will attack if they smell meat. Occasionally spawn colonies by building mud and straw huts.
Insectoids - A primitive race of swamp dwelling mutants closely resembling insect people. They are fast and stealthy and often ambush travellers through the swamps. They fight with blowpipes and bows.
Wild tigers - rare at first but eventually become more abundant. Escaped from zoos and breeding in the wilds.
Wild Lions - rare at first slowly becoming more abundant. Escaped zoo animals
Wild Gazelle - like all the zoo animals rare, but growing slowly in abundance.
Wild Zebra - Escaped zoo animal (see above)
Wild Gorilla - Escaped Zoo animal
Wild Ostrich - Escaped zoo animal
Wild Giraffe - Escaped zoo animal
Giant Cobra - Snakes mutated by the goo to grow in size to be able to eat the large insects and rodents
Giant Adder - Mutant snake (see above)
Giant Mamba - Mutant snake
Fungaffids - Fungaloid Triffids or Triffid fungaloids? A rare harmony between the two creatures creates these outcasts of both species
Cephaloposiden - Rare giant cephalopods that appear rarely in rivers. Jabberwoks of the ocean
Shades - Smokey black creatures from the portals. Only damageable in light.
Reapers - Basically stronger, rarer shades. Only damageable and visible in light.
Fishkin - Rare fishlike mutants that spawn near rivers. Occasionally form colonies on the river banks.
Asylum escapees - Insane escapees from asylums. Attack everyone and everything. (I mean everything, trees, traps, monsters, player, cars, walls) Who knows whats going on in their heads.
Demons - Formed from magma below the surface which has been directly exposed to the portals. They drip pools of magma everywhere. Slowly shrink into insignificance as they travel (and drip) more. Careful though, they can set anything on fire in a 1 tile radius around them.
Ill add more as I think them up, enjoy