Mobs will ordinarily wander around at random and usually avoid walking off blocks high enough to cause falling damage, though they can be fooled by non-solid blocks such as open trapdoors. In this state, hostile mobs (besides ghasts, Endermen, and zombies) have a search radius of 16 blocks.
Mobs are capable of climbing ladders just as the player is: if they try to move toward a ladder they're touching, they move up it instead. Mobs do not willingly climb ladders, even when aggressive (with the exception of slimes, magma cubes and blazes), and do not see ladders nor do they pathfind up them, so they will not attempt to avoid falling off a ladder should they be on the edge of one. Spiders and cave spiders can climb all blocks as if they were ladders (but only to a limited height).
All mobs except slimes, magma cubes and ghasts will stop wandering within 5 seconds if there is no player within a 32 block radius. In this state, they will glance around randomly, but they won't walk anywhere, although they can still be moved by other means such as flowing water, minecarts, etc. Zombies can walk when there is a villager they can attack even if they are over 32 blocks from a player; similarly, villagers will flee when there is a zombie chasing them.
Most mobs have an advanced pathfinding system that allows them to traverse complex mazes to get to the player. Here is a video showcasing their path finding system.
Passive mobsPassive mobs will not attack the player under any circumstances, rather if damaged directly by the player, they will run around in a random pattern (except squid). This category includes most of the "farm animals" present in the game, which can be bred for food and/or other resources. Also included are bats and squid, both of which have special spawning conditions and cannot be bred. Ocelots are technically passive, in that they will not attack the player, but are actually coded as hostile mobs.
Animals are attracted to both light and grass. If there is a lot of grass nearby, they will wander toward it regardless of light level. If they are completely surrounded by grass, they will wander aimlessly. If they can't see any grass, they will wander toward light. Baby farm animals will follow fully grown farm animals of their species. Passive mobs will flee randomly when attacked. Unlike hostile mobs, most passive mobs (including neutral wolves) will not despawn when the player moves away from them; the exceptions are squid, ocelots, and bats.
Most passive mobs will follow a player who is holding their specific food item: wheat (cows and sheep), carrots/potatoes/beetroots (pigs), or seeds (chickens). As long as the player does not get too far ahead of the mob, they will follow the player over long distances. This can be used to corral mobs into pens. If the food is given to the mob by right clicking the mob, the mob will enter breeding mode (indicated by red heart particles rising off the mob. Horses can also be tamed and bred, but the player must mount the horse and feed it apples before being thrown off (in order to tame).
Neutral mobsThis includes Endermen, zombie pigmen, wolves, and (bright light) spiders and cave spiders. Neutral mobs do not attack the player unless provoked. The act of provoking varies between each mob.
Wolves merit their own discussion. Much as with zombie pigmen, if a wolf is attacked, all wolves in the area will permanently become hostile to the player and attack them. However, wolves are not as common as zombie pigmen are (in the Nether), as they appear only in Forest and Taiga biomes, and then only in small groups. Accordingly, it's almost trivial to avoid attacking them. Wolves which have not become hostile can be tamed by feeding them bones. While they don't change their appearance as drastically as ocelots do, they effectively become dogs, with a dyeable collar and much higher health. Once tamed, they will fight for the player, targeting any mob that attacks the player (including skeleton arrows), or which the player attacks (not including missiles). Dogs can be healed or bred by feeding them any sort of meat (but not bones).
Hostile mobsIf the closest player to a wandering hostile mob is within the search radius of 16 blocks and a line of sight can be drawn, the mob will enter pursuit mode. In this mode, will attempt to attack the player, and will find the quickest route to get to the player. Mobs will cease attacking if the player moves out of their vision, but if the player directly hits a mob, it will be able to see the player through blocks. Most mobs will float in water, and whilst in pursuit mode, can pathfind around walls to get to the player. When certain hostile mobs are attacked by another one, it will attack the attacking mob. For example, when a skeleton arrow hits a zombie, the zombie will attack the skeleton. If the mob burns when exposed to daylight, it will seek cover (out of direct sunlight) or water, which will prevent them from burning.
Mobs are capable of climbing ladders just as the player is: if they try to move toward a ladder they're touching, they move up it instead. Mobs do not willingly climb ladders, even when aggressive (with the exception of slimes, magma cubes and blazes), and do not see ladders nor do they pathfind up them, so they will not attempt to avoid falling off a ladder should they be on the edge of one. Spiders and cave spiders can climb all blocks as if they were ladders (but only to a limited height).
All mobs except slimes, magma cubes and ghasts will stop wandering within 5 seconds if there is no player within a 32 block radius. In this state, they will glance around randomly, but they won't walk anywhere, although they can still be moved by other means such as flowing water, minecarts, etc. Zombies can walk when there is a villager they can attack even if they are over 32 blocks from a player; similarly, villagers will flee when there is a zombie chasing them.
Most mobs have an advanced pathfinding system that allows them to traverse complex mazes to get to the player. Here is a video showcasing their path finding system.
Passive mobsPassive mobs will not attack the player under any circumstances, rather if damaged directly by the player, they will run around in a random pattern (except squid). This category includes most of the "farm animals" present in the game, which can be bred for food and/or other resources. Also included are bats and squid, both of which have special spawning conditions and cannot be bred. Ocelots are technically passive, in that they will not attack the player, but are actually coded as hostile mobs.
Animals are attracted to both light and grass. If there is a lot of grass nearby, they will wander toward it regardless of light level. If they are completely surrounded by grass, they will wander aimlessly. If they can't see any grass, they will wander toward light. Baby farm animals will follow fully grown farm animals of their species. Passive mobs will flee randomly when attacked. Unlike hostile mobs, most passive mobs (including neutral wolves) will not despawn when the player moves away from them; the exceptions are squid, ocelots, and bats.
Most passive mobs will follow a player who is holding their specific food item: wheat (cows and sheep), carrots/potatoes/beetroots (pigs), or seeds (chickens). As long as the player does not get too far ahead of the mob, they will follow the player over long distances. This can be used to corral mobs into pens. If the food is given to the mob by right clicking the mob, the mob will enter breeding mode (indicated by red heart particles rising off the mob. Horses can also be tamed and bred, but the player must mount the horse and feed it apples before being thrown off (in order to tame).
Neutral mobsThis includes Endermen, zombie pigmen, wolves, and (bright light) spiders and cave spiders. Neutral mobs do not attack the player unless provoked. The act of provoking varies between each mob.
Wolves merit their own discussion. Much as with zombie pigmen, if a wolf is attacked, all wolves in the area will permanently become hostile to the player and attack them. However, wolves are not as common as zombie pigmen are (in the Nether), as they appear only in Forest and Taiga biomes, and then only in small groups. Accordingly, it's almost trivial to avoid attacking them. Wolves which have not become hostile can be tamed by feeding them bones. While they don't change their appearance as drastically as ocelots do, they effectively become dogs, with a dyeable collar and much higher health. Once tamed, they will fight for the player, targeting any mob that attacks the player (including skeleton arrows), or which the player attacks (not including missiles). Dogs can be healed or bred by feeding them any sort of meat (but not bones).
Hostile mobsIf the closest player to a wandering hostile mob is within the search radius of 16 blocks and a line of sight can be drawn, the mob will enter pursuit mode. In this mode, will attempt to attack the player, and will find the quickest route to get to the player. Mobs will cease attacking if the player moves out of their vision, but if the player directly hits a mob, it will be able to see the player through blocks. Most mobs will float in water, and whilst in pursuit mode, can pathfind around walls to get to the player. When certain hostile mobs are attacked by another one, it will attack the attacking mob. For example, when a skeleton arrow hits a zombie, the zombie will attack the skeleton. If the mob burns when exposed to daylight, it will seek cover (out of direct sunlight) or water, which will prevent them from burning.
Boss MobsThere’s currently two boss mobs in minecraft, though more may be implemented in the future. Boss mobs are much stronger and move and attack in specific ways. Only 1 boss mob will be spawned per world, though more could be spawned in through mods.
The Ender DragonThe Ender dragon is the first and currently only boss monster and dragon in minecraft. It lives in the End, along with many Endermen.
Behavior
The Ender dragon is the most difficult monster to kill and it takes a very long time to do so. The dragon’s health is 100 hearts, which means it would have to be hit over 20 times with a fully drawn bow. However, inside the End are Ender crystals on top of huge obsidian pilars which will heal the dragon when it flies close enough, so destroying them first is highly recommended and pretty much a requirement when you’re on your own.
The Ender dragon attacks by flying against you, which not only does 5 hearts worth of damage, it also pushes you back a lot. It can easily push you off of an obsidian pilar, which will kill you through fall damage alone. Wearing a full set diamond armour is almost a must as it will absorb 80% of the damage.
The Ender dragon is capable of flying through all blocks, which will destroy those blocks on impact, with the exception of end stone, bedrock and obsidian. Large amounts of obsidian are advised, though not necessary, to create an understructable path to the top of the obsidian pillars. Anything else often ends up being destroyed by the dragon, leaving you without a fast way back down.
When the Ender dragon dies, it’ll start to disolve in mid air while beams of light shine out from within it’s body. After it has disolved, it’ll explode into 20.000xp points worth in orbs. A portal will also be created on the land directly under him. The portal has a dragon egg resting on a pilar in the middle of it. The portal will lead you back to the Overworld.
The xp orbs will take you to anywhere between level 100 and 110. Despite always dropping the same amount of xp, the levels you gain aren’t always the same, this has to do with the mechanics of how xp is calculated per level.
There’s always only 1 dragon per map, unless another one is spawned in through the use of codes or mods. On multiplayer servers admins often spawn in 1 or more Ender dragons as a fun event for the whole server.
Behavior
The Ender dragon is the most difficult monster to kill and it takes a very long time to do so. The dragon’s health is 100 hearts, which means it would have to be hit over 20 times with a fully drawn bow. However, inside the End are Ender crystals on top of huge obsidian pilars which will heal the dragon when it flies close enough, so destroying them first is highly recommended and pretty much a requirement when you’re on your own.
The Ender dragon attacks by flying against you, which not only does 5 hearts worth of damage, it also pushes you back a lot. It can easily push you off of an obsidian pilar, which will kill you through fall damage alone. Wearing a full set diamond armour is almost a must as it will absorb 80% of the damage.
The Ender dragon is capable of flying through all blocks, which will destroy those blocks on impact, with the exception of end stone, bedrock and obsidian. Large amounts of obsidian are advised, though not necessary, to create an understructable path to the top of the obsidian pillars. Anything else often ends up being destroyed by the dragon, leaving you without a fast way back down.
When the Ender dragon dies, it’ll start to disolve in mid air while beams of light shine out from within it’s body. After it has disolved, it’ll explode into 20.000xp points worth in orbs. A portal will also be created on the land directly under him. The portal has a dragon egg resting on a pilar in the middle of it. The portal will lead you back to the Overworld.
The xp orbs will take you to anywhere between level 100 and 110. Despite always dropping the same amount of xp, the levels you gain aren’t always the same, this has to do with the mechanics of how xp is calculated per level.
There’s always only 1 dragon per map, unless another one is spawned in through the use of codes or mods. On multiplayer servers admins often spawn in 1 or more Ender dragons as a fun event for the whole server.