Zombie
Zombies are the most common hostile mobs. They spawn in dark or dimly lit areas, and will attack the player by slowly moving toward them and inflicting damage by making contact. Like Skeletons, Zombies catch fire in sunlight. Zombies can be heard making roaring, moaning and growling noises when near. Zombies can be damaged by health potions.
In addition to generic Zombies, which closely resemble an "undead" version of the Player, several rarer Zombie forms may spawn. Zombie Villagers comprise 5% of all spawned Zombies. They generally behave as ordinary Zombies, but their character model's head and face is reminiscent of that of a villager, especially the nose. Zombie Villagers may occur in any game mode or difficulty except Peaceful.
Zombie Villagers can result from Zombie attacks on ordinary Villagers. If any type of Zombie kills a Villager, there is a chance that the Villager will transform into a Zombie Villager (100% in hard difficulty, 50% in normal, 0% in easy). This often occurs during sieges.
Zombie Villagers can be cured by throwing a Splash Potion of Weakness at them, then feeding them a Golden Apple by right-clicking on the Zombie Villager with it. A loud hissing sound will be heard if successful, and the Zombie Villager will begin to shudder. The transformation will take 2–5 minutes, during which time the Zombie Villager will still attack and must be shielded from other attacks and sun damage. While the zombie is being cured, it will have the Strength I effect in normal difficulty, or Strength II in hard difficulty, making it more important to isolate the zombie. Baby Zombies make up 5% of zombie spawns. Chicken Jockeys are an extremely rare variant of the baby zombie.
Along with Skeletons, some spawned Zombies can pick up dropped items from the ground. These Zombies will automatically hold any item they come across, but if those items happen to be Armor, Weapons, or Tools, the Zombie will wear them. Some of these Zombies spawn already sporting such items, and those items may also be enchanted. The chances of that event are listed below and are taken from the game's code. Zombie villagers can spawn naturally with armor on.
If a zombie does spawn with armor, it will always include a helmet, and a 10% to 25% chance of each other piece (depending only on difficulty)
Almost all Zombie armor has no durability score, which means it cannot "wear out" the way player armor does. Helmets on Zombies that usually wear away while on a player (meaning not a block) can wear away and break on a Zombie if the zombie is exposed to daylight and the Zombie starts burning like usual.
When killed, Zombies drop 0–2 pieces of Rotten Flesh. These can be eaten by the player, but have an 80% chance of giving the player food poisoning. Unless a player is doing a lot of strenuous activity eating rotten flesh and getting poisoned by it will add 2 to the hunger bar and then slowly take 2 away (sometimes only subtracting 1.5 or 1). In addition the food poisoning doesn't stack (it just resets the countdown each time) so waiting until your hunger bar is down to 2 and eating 4 rotten flesh will boost you to 10 then erode down to 8, giving a net gain overall. In addition rotten flesh can safely be used to heal and breed tamed Wolves without any risk of the Wolf becoming poisoned.[4] Zombies will rarely drop iron ingots, carrots and potatoes. If a Zombie spawns with a Sword, Shovel or some Armor there is a small chance of it dropping one or more of its items. This is one of two ways to get the uncraftable Chain Armor in Survival mode, the other being trading with a blacksmith.
Zombies spawn in groups of 1-6 and will pursue the player on sight. Zombies will attempt to avoid obstacles, including sheer cliffs and lava, and will try to find the shortest path towards the player. (video demonstrating the Zombie's path finding) Unlike Skeletons, Zombies do not try to avoid being hit, and continue to pursue the player even when being attacked. Zombies can sometimes deal damage through a closed door, as shown on the picture to the right. Like most mobs, Zombies will always float on water, even if their target is below them. At dawn, generally when the sun is 15 degrees or more above the ground (that is, when the moon can no longer be seen), most Zombies will catch fire and burn once exposed to direct sunlight. However, zombies with head armor are immune to sunlight, but the armor piece will take damage. They may make some attempt to seek out shade during this time, or enter bodies of water to protect themselves from burning up. Being in water, rain, or shade negates the effects of direct sunlight, preventing them from burning. Zombies will exit protective areas to chase a close player or Villager, whereupon they will again be vulnerable to burning. Zombies wearing headgear will also be protected from burning, and Baby Zombies do not burn. If they attack a player or mob while burning, they will set their victim on fire.
Zombies will attack Villagers within 16 blocks. Once a Zombie has focused on a Villager, the Zombie will ignore any other Villagers, and the player, until its target is dead or the player attacks. Zombies will bang on closed wooden doors, and can succeed in breaking them down in Hard difficulty. In other difficulties, the door will crack, but not break. Iron Doors are always safe. In Minecraft Pocket Edition, zombies cannot break down wooden doors at all. In the newest updates, not all zombies will break down doors. Only zombies with a special tag can do this; since the chance of this happening is ridiculously low, only rarely will one see a zombie attack a door. If a zombie is attacking a villager and is hurt by another mob, the zombie will then retaliate and attack the offending mob.
On Hard difficulty, Zombies can call other Zombies in the area to "help", and in a matter of seconds, more Zombies will target the player. When a zombie is damaged by another entity it will attempt to spawn one reinforcement zombie nearby (within an 80x80x80 box centered on the attacked zombie). Both the damaged zombie and the new zombie will have a reduced chance of summoning another reinforcement, so they cannot cause an infinite number of zombies to spawn, but they can multiply significantly. Damaged zombies will also call all other nearby zombies in the area to attack, regardless of difficulty, like zombie pigmen. These effects can be combatted by killing the zombie in as few hits as possible, by using environmental damage such as falls or lava, or by ignoring them.
A lone zombie can easily become a large group, as it can spawn more zombies. Furthermore, they hit a lot harder when injured. Killing the zombie rapidly (iron or diamond sword), or leading with environmental damage, can help cut the multiplication. Blocking the zombies off with fences works fairly well, but be wary that reinforcement zombies can appear and approach from all directions.
It is possible to "preserve" zombies many days for the purpose of using them either as a form of defense, or to cure a zombie villager without a risk of it dying in sunlight before turning back into a Villager. The most effective way to stop a zombie from burning in sunlight for preservation purposes is to put a helmet or pumpkin over its head, as if the zombie escapes its prison outside during daytime, it may have a risk of burning to death without the head protection. If it is a pumpkin, the zombie will never burn, because helmets eventually burn away under the strong sun. However, if it is a helmet, it gives defense unlike a pumpkin. Giving a zombie any type of head protection may prevent it from despawning. Naming a zombie using a Name Tag will also prevent it from despawning, however unless you have a very large number of tags, this is not recommended.