The Following list is that of animals that could be added to the game using current models that can be easily recoloured/resized/changed stat wise by you and would provide innumerable hours of gameplay experience hunting each type down.
Polar Bear - a bear seldom found in the snow biome on mountains is a recoloured bear to a white has 1.5x stats of current bear due to being so tough from the cold and harshness of the mountain.
Gives same as a normal bear but hides are white and make a recoloured teddy bear that yield more lp

Black Bear - a bear that is found in caves and primarily dark forest terrain is 2x the strength of normal bears and scaled to be a little larger to make look more imposing. this bear would also have a special attack at say 10 ip called "pat of the black paw" that would ignore armor making it crucial to beat it as fast as possible or use steal thunder or else you will get rekt.
Same as of the polar bear with the black teddy bear giving nice lp but also adding a curio that could give 20-40k lp over 24-48 hours (Heart of the Black Beast) making these animals a risky fight, but overall rewarding and something you wish to set out to find and engage.
Baby Bear - a resized version of any bear that spawns with the parent bear in numbers of 1-3 and will fight when engaged but runs when hit once. yields less, has less stats. this is a great way for newbies and weaklings to fight a bear and get bear skins (x1) but risky if they aggro the parent.
added feature to baby bear, chance for a maw on butcher this would help with those of us that have trouble getting maws and we can also have more recipes that use maws and goldbeaters and a new source for maws on top of just farming.
Black/Yellow/Green/Red Deer - an expanded recolour of current deer giving each deer more stats and varying base q. for example Black deer are 50q base but 2x stats of red current deer, yellow is 1.5, green is 1.2, red is current deer. also each stage yields more meat, so if you are out hunting you can decide do you want a harder fight and more meat or an easier fight and less meat.
new curio deer doll - uses hide wool and antlers to make a respective black/yellow/green/red deer.
Bambi Deer- smaller version of deer, ai path finding makes them run randomly around and making them hard to catch and fight, yields a maw.
Wolves- recoloured version of current fox model to grey spawns in packs of 3-6 (the derpy bounding is a must because of how funny it would be getting chased by them). Spawns on mountains, grasslands and that red coloured biome or the yellow one.
Their pathfinding is a follow the leader style where one is in the alpha and if engaged and defeated the others will fight each other or run away making the fight become that of bring your friends and take each 1v1 or tank them all and zerg down the leader fast. Can yield wolf cape down the track, but for time being meat and wolf skull. stat wise these are a about as tough as a badger if not more. too strong and they become gank squads too weak and they become groupies.
Giant Toad - spawns in swamps only. tough SOB and is same model as a current toad and attack animation is the its current jump animation. stats about 100-200ua 50-100 hits etc.
unique type loot as its a swamp creature and can be rare, it would also make sense that its loot is also quite good such as butchering only yielding toadstools(1-10) crowns(1-10) bluebells(0-2) dragonflies (1-5) and also toad eyes/tongue for curio or ingredient for something.
Giant Spider - uses the model of itsy bittsy spider scaled up and spawns in caves, strong scary creature.
Yields spiderlegs(food) fangs(arrow) and poison sac (curio) silk sac (boil for silk thread/spiderweb). Chance on death to be mother spider and releases tons of itsybitsy spiders that you have a few seconds to grab as many as you can before they despawn.
Ancient Knight- now this might sound very crappy idea, but these use same sprites as players so you dont know if they are a player when you encounter one unless you notice armour and even then it could be a player wearing the armour.
As any mob the best thing about this is the armour can be very good or crap and the shield it carry's could be different colours or models and a way to insert randomly rare items into the game for example tower shields or maces helmets etc, but for time being its just a standard fighter wearing steel/ bronze /leather.
Haunted Chest - with the addition of Wraiths thanks to latest patch we can now have chests spawn in the map randomly that are guarded by a Wraith or varying strength. the wraith gives no loot as you want the chest and the chest can yield potentially anything from curios/food/weapons and armor to absolutely nothing.
added bonus is its a LC recoloured black or silver so that even if you find nothing the fact its a different coloured chest would be enough imo to risk it.