Hostile Mobs
Hostile mobs attack the player under all circumstances. If a undead mobs that burn in the sunlight is wearing a halmet of any kind, it will not burn in the sunlight.
Zombie, Husk, Drowned, and Zombie Villager
Note: The reason why these are all under the same box is because they are all very similar, and I would have to go over the same things for each one. All variants of zombies attack players, villagers, and turtle eggs, and like most other undead mobs, zombies burn in the sunlight. If a zombie is in a desert, it has a high chance of becoming a husk. If a husk is fully submerged underwater for a long period of time, it will become a regular zombie and if a zombie is fully submerged in water for a long period of time, it will become a drowned, and in Bedrock dropping all armor in the process. If a player is at a village that has 10, 20, or 30 beds and 20, 40, or 60 villagers at midnight, a siege can start, spawning up to 20,40, or 60 zombies, depending on village size. Baby zombies  are 30% faster than adult zombies, and will never grow into adults. Baby zombies also can ride a large selection of mobs. Zombie villagers can be cured by splash potions of weakness, and golden apples. When a player is attacked by a husk, they will get the hunger effect. Drowned can swim in water, and have a chance of spawning with tridents, and are able to throw them infinetly. Zombies pursuing a villager bang on doors, and on hardcore mode, can break doors down. In Java edition, zombies have a chance of picking up items.
Skeleton and Stray
Skeletons spawn in every biome, except for end biomes, and mushroom islands. If a skeleton spawns in a Snowy Tundra, Snowy Mountains, Ice Spikes, Frozen River, Frozen Ocean, and Deep Frozen Ocean biome, it has an 80% chance of becoming a stray. Skeleton horsemen, and skeleton traps are in the skeleton horse description. Skeletons naturaly spawn with bows, and about 11% of those are enchanted in some way. When killed, skeletons have a chance of dropping bones and arrows. Skeletons attack iron golems, and baby turtles, and flee from wolves. Strays shoot slowness arrows at the target, giving the target the slowness effect. If a creeper is killed by a skeleton, it drops a music disc.
Creeper
Creepers are different then any other mob, in which the inflict damage by exploding, killing themselves in the process. If a creeper is struck by lightning it becomes a charged creeper, that does more explosive damage, and makes a bigger crater. When killed, creepers have a chance of dropping gunpowder. Creepers can also be forced to explode via flint and steel. (Java edition) If a creeper explodes with a status effect on, it creates an area effect cloud.
Slime
Slimes spawn in swamp biomes, and special "Slime chunks". Slime spawn in 3 sizes, the first of which can deal no damage to the player, the second, slightly bigger one can deal damage to the player, and the third, biggest one deals the most damage. If a large slime is killed, it turns into a couple medium slimes, then when medium slimes are killed, they turn into a few small slimes, once those are killed, they have a chance of dropping slime balls.
Silverfish
Silverfish can only be spawned by a silverfish spawner, or by a player breaking an infested block. Those blocks include stone, cobblestone, stone bricks, mossy stone bricks, cracked stone bricks,  chiseled stone bricks, granite, andesite, and diorite. Silverfish drop nothing when killed.
Endermite
Endermites can only be spawned by a player throwing an ender pearl, and has a 5% chance of doing so. Endermen attack endermites, and like zombie pigmen, endermites around the one being attacked target the attacker. Endermites drop nothing when killed.
Witch
Witches can spawn anywhere in the overworld with a low light level, besides mushroom islands. They also spawn in witch huts in swamp biomes, along with a black cat, neither of which can despawn. If the original witch is killed, other witches can spawn, without a black cat, and can despawn. Witches can also spawn with raids. If a villager, or baby villager is struck by lightning, it will become a witch. Witches attack the player by throwing splash potions at them, and can heal themselves with potions too. Witches have a chance of dropping redstone, glowstone dust, glass bottles, sticks, sugar, and spider eyes. witches must drop 1-3 different items when killed, and 0-2 of each of those.
Evoker
Evokers are only able to be found during raids, and at woodland mansions, that attack by summoning vexes, and evoker fangs. Evoker fangs come out of the floor, and bite down, before disappearing back underground, and if the player is bit, armor doesn't help, but enchantments on the armor do. Vexes are hostile mobs that evokers can spawn, if you want to learn more about them, find the vexes description under this one. Once killed, evokers drop a totem of undying (Looting does not affect this number) and have a chance of dropping an emerald, and if it was a raid leader, an ominous banner too. Evokers can also dye blue sheep red, but it doesn't change anything except for the color. Evokers also attack villagers, baby villagers, iron golems, (snow golem in Bedrock), and wandering traders.
Vex
Vexes are only able to be found if a evoker summons them. Besides for players, vexes attack villagers, iron golems, wandering traders, and in bedrock edition, snow golems. Vexes can fly through walls, water, and lava without taking any damage. Vexes can't drop their sword, unless the player has looting.
Vindicator
Vindicator spawn in woodland mansions, raids, and on hard mode, patrols. Vindicators are like pillagers, but instaid of crossbows, they have iron axes. If they spawn at a woodland mansion, they will not despawn. Vindicators are hostile towards villagers, iron golems, snow golems, and wandering traders. When killed vindicators have a chance of dropping an emerald, and if it is a raid leader, an ominous banner. If on bedrock edition, they have a chance of dropping emeralds, any part of iron armor, an iron axe, an iron shovel, or an iron sword.
Pillager
Pillagers spawn in raids, patrols, and at pillager outposts. Pillagers are like vindicators, except they have crossbows instead of iron axes. Pillagers are hostile towards players, adult villagers, iron golems, snow golems, and wandering traders. Pillagers have a chance of dropping their crossbow, and if they were a raid leader, they drop their ominous banner. If on bedrock, they also have a chance of dropping arrows, any part of iron armor, an iron axe, sword, or shovel. If a player kills a pillager with the ominous banner on the pillager head, the player will get the bad omen effect. If a player goes into a village with the bad omen effect, it will start a raid.
Ravenger
Ravengers can only spawn during raids, and only past wave three of one. Ravengers can be ridden by illagers, but if a ravenger goes under water, the illager is dismounted. Ravengers cannot be ridden by players. Ravengers have a chance of dropping a saddle when killed. Ravengers are hostile towards players, villagers, iron golems, snow golems, and wandering traders.
Phantom
Phantoms can only spawn if a player hasn't slept in three game days, but the player able to see the sky, so they cannot be under a block unless it's glass. When killed phantoms drop phantom membrane, which can be used to repair elytra. Phantoms are considered undead mobs, so they burn in sunlight. Like creepers, phantoms ae afraid of cats.
Guardian
Guardians only spawn is ocean monuments, naturally spawning structures in ocean biomes. Guardians are sort of like pufferfish, When they are swimming, their spikes retract, but when they stop swimming, their spikes come out, if the player touches them, they take damage. They have another attack where they shoot a laser out of their eye, waiting a couple seconds before dealing damage. As time progresses, the laser goes from purple to bright yellow, showing that it's about to do damage. When killed, guardians have a chance of dropping raw cod, and prismarine crystals. Guardians are also hostile towards squid.
Elder Guardian
Note: Elder guardians are considered a boss mob if you play on bedrock edition. Every time a ocean monument generates, three elder guardians spawn in different rooms. Elder guardians give the player mining fatigue, making it practically impossible to mine blocks. Once killed, elder guardians drop a sponge, and have a chance of dropping prismarine shards, prismarine crystals, and raw cod. Like a regular guardian, its spikes extract when they stop swimming, and their lazer is the same, waiting a couple seconds before dealing damage. As time progresses, the laser goes from purple to bright yellow, showing that it's about to do damage. Besides for being bigger, elder guardians also have more health than regular guardians.
Blaze
Blaze can only be found in nether fortresses, they do spawn naturally, but there is also blaze spawners in nether fortresses. Blazes can shoot three fireballs in a row, before being extinguished, and has to wait 5 seconds before firing again. If a player is hit by a fireball, they are lit on fire. If a player comes into contact with a blaze, the player takes damage. Once killed, blazes have a chance of dropping blaze rods.
Wither Skeleton
Wither skeletons spawn naturally in nether fortresses, are three blocks tall, and have a stone sword. Wither skeletons attack with the sword, and if a player is hit by one, they get the wither effect. When killed, wither skeletons have a chance of dropping bones, coal, and a small chance of dropping a wither skeleton skull. Wither skeletons are hostile towards iron golems, snow golems, players, and piglims. Wither skeletons are scared of wolves.
Ghast
Ghasts only spawn in the nether, and are the second largest mob in the game. Like blazes, ghasts shoot fireballs at the player, but one at a time, instead of three. Once killed, ghasts have a chance of dropping a ghats tear, and gunpowder. Ghasts are only hostile towards the player, and nothing else. Unlike most mobs, ghasts will not try to move closer to the player.
Magma Cube
Magma cubes are the slime of the nether, coming in large, medium, and small sizes, all three of which can do damage to the player. Like slimes, the large one becomes medium ones, and the medium ones become small ones. Once killed, magma cubes have a chance of dropping magma creme. Unlike most other mobs, magma cubes have no path finding abilities, and will jump off cliffs.
Hoglin
Hoglins have not been released yet, but will be added in the nether update. Hoglins spawn in crimson forests, and bastion remnants. Hoglins don't like warped fungus, and try to stay away from it. Even though they are hostile, hoglins can still be put on a lead. Once killed, hoglins have a chance of dropping leather, and must drop at least two raw porkchop. Hoglins attack on site, shooting the player into the air, the baby hoglins also attack, but cannot shoot the player into the air. If a hoglin is brought to the overworld, or the end, after about 15 seconds they will turn into a zoglin. hoglins are the only hostile mob that can be bred, and are bred using crimson fungus.
Zoglin
Like the hoglin, this mob hasn't been released yet. Unlike hoglins, zoglins are immune to fire damage, and are hostile towards most other mobs. Zoglins must drop at least one rotten flesh when killed. Zoglins aren't scared of warped fungus, and cannot be bred. They attack the same way as regular hoglins.
Shulker
Shulkers are found in end cities, and have a chance of dropping shulker shells. Shulkers attack by shooting projectiles out of their open shell, and if they hit the player, the player will start to levetate. Shulkers can also teleport to different blocks, and this is the only way they can move. Shulkers can also be dyed, like sheep. When the shulkers shell is closed, it takes less damage, and is immune to arrows.
