Sharks
Sharks are predatory fish found in the oceans. They may attack players who have already been damaged, as they smell the fresh blood, but do not attack healthy players. Other mobs are not as fortunate...
Piranha
Voracious fish found in jungle ponds. They only attack when their target is weak. Rumour has it they can strip a person or horse clean to the bones...
Deer
Cowardly herbivores found in all sorts of forests. They run from larger mobs, but can be bred with wheat or carrots
Coyotes
Coyotes are opportunistic hunters and scavengers, and will even attempt to prey on players in the night. However, in the day they can be tamed with raw rabbit or chicken. They spawn in deserts, mesas, and plains.
Lammergeier/Bearded Vulture
Large birds found in deserts and mountains. They eat bone marrow, and will grab skeletons and drop them down to break their bones open. They can be tamed with bones
Eels
Comes in both saltwater and freshwater variants, they're neutral, but don't hold food near them...
Badgers
Badgers can be found in forests, savannas, and taigas, and will prey on smaller animals such as chickens. If attacked, badgers will throw dirt and other such materials at the attacker, on top of using their sharp claws
Giant Squid
Even bigger than their cohorts, and are much nastier. Some believe they can rip you from your boat in the night and crack your skull with their beak
Horseshoe Crab
These harmless living fossils can be found in beaches and oceans, and drop bonemeal and their meat when killed
(Updated) Feral Wolves
Hostile wolves found in forests and taigas. If a player wears the head of a Dragon, they can tame these beasts with bones. Killing a feral wolf may drop their head, as well as some pelts, which can be made into capes, leather, and wool
Flying Fish
Whimsical fish found in warmer oceans, they may jump from the water and glide a bit
Reindeer
Reindeer can be found in any cold biome, and can be bred with wheat or carrots. Reindeer can also be ridden!
Brown or Grizzly Bear
Moose
Moose are large members of the deer family found in taigas and swamps. Moose are a force to be reckoned with, but slaying one nets you a lot of venison and possibly a head.
Jellyfish
Jellyfish spawn in water and float aimlessly, but don't touch them! They will inflict poison and blindness!
More Lammergeiers
A Flock of Pheasants in a forest
Despite their textures, any 2 adults can breed with pumpkin seeds, and drop their meat when killed. Pheasants also peak at the ground!
Black Bears
Octopus
Neutral and befriendable cephalopods found in oceans. Give them fish and they will be quite powerful allies. That is, as long as you avoid the blue-rings
Walrus
Neutral semi-aquatic animals, drop leather and blubber when killed, but won't give up easily. But who was the walrus?
Lamprey in a lake
Turkeys
Turkeys are semi-neutral, semi-timid birds found in forests and similar. They will attack back, but scatter afterwards. When attacking or breeding, they flare their tail. Killing one may give you a nice feast! Any 2 adults can breed with pumpkin seeds.
Songbird in a tree
Lampreys
Lampreys are parasitic fish. They will cling onto things bigger than them in order to suck their blood. Be careful in water!
Boar
Boars are vicious piggies found in many biomes, including forests, jungles, and savannas. Some will attack larger creatures on sight, and most will attack smaller creatures like chickens and pheasants. Drop pork meat and sometimes their head.
Colossal Squid
Large, predatory squids found in deep oceans at night... don't get too close
Whales
Whales are (mostly) peaceful mammals found swimming in the oceans of Minecraftia. That doesn't mean its a good idea to annoy them.
Bobbit Worm
Found in oceans, Bobbit Worms bury their entire body aside from their vicious mouths into soft sediment in order to ambush passing prey, including people.
Crabs
Crabs can be found on Beaches and in Swamps, and drop Crab Meat and Bonemeal when killed. Crabs also like to party, but they won't join any ol party
Barracuda
Aggressive predatory fish found in open waters in warmer climates. They are strong enough to break bones by ramming targets! Known for their attraction to shiny armor.
Tarantulas
Tarantulas spawn in deserts, mesas, and jungles, and are hostile. They may even fire some of their blindness-inducing hairs at enemies
Dragonfly
Harmless ambiance bugs found in swamps and rivers, they come in many colours and may be bottled
Butterflies
Harmless ambiance bugs, they will pollenate crops, can be caught in a bottle, and generally improve any garden
Nautilus
Nautili are harmless oceanic mobs that drop raw fish when killed. However, if in 1.14, they may also drop their shell
Songbirds
Songbirds are common sights in forests. They are harmless and will try to fly away from players, but they do enjoy eating seeds.
Squirrels
Squirrels are timid rodents found in forests. If frightened, they will flee and try to scurry up trees. They can be bred with seeds.