Zombified Piglin

Zombie Pigmen are neutral mobs that first appeared in Minecraft alpha and are currently one of two mobs that spawn in the Nether. Since Beta 1.5, pigs that are struck by lightning in the regular world will become a zombie pigman. Cooked porkchops are dropped by dead Zombie Pigmen, and are therefore a renewable source of food in the Nether.

Behavior
Zombie Pigmen wander around aimlessly, avoiding cliffs and Ghasts. If you stand near a Zombie Pigman, it will turn its head towards you for a few seconds, then resume its wandering. Pigs also have this behavior. Zombie Pigmen spawn in packs of 4-10 and tend to stay together. It seems, however, if space is limited (for example, a narrow tunnel), they may spawn in smaller groups or even alone. Attacking one Zombie Pigman will cause the entire group to become hostile, often swarming the player. This can make them very deadly when in a group due to each zombie pigman dealing 2.5 hearts of damage. If the player moves a certain distance from a pack, waits a while or leaves the Nether and returns, they will become neutral again. Switching the difficulty to Peaceful will cause them to de-spawn completely and reset their neutrality in other difficulties. Once entering their territory they will stop and stare for a few seconds and continue walking around.

Fighting
Zombie Pigmen in groups are incredibly dangerous and should not be fought without adequate preparation. They swarm the player and can kill very quickly; if the player attempts to run away and then shoot them from far away, even more Zombie Pigmen will become aggressive. In order to fight a group of three or more, a player should have armor, a sword (preferably diamond), a bow, one or two stacks of arrows, and several pieces of food (mushroom soup or cooked porkchops). The player should then dig a tunnel into the side of the mountain to ensure that the zombies only come from one direction. The player can then shoot them, retreat into the tunnel, machine-gun shoot them down, and use the sword if they get too close. If there is only one Zombie Pigman nearby, you can kill it even barehanded. If there are two, you can kill them with a bow easily. Be aware, if they kill you and you return quickly, they will still be there, and they will still be aggressive.

Trivia

 * Zombie Pigmen are mostly immune to lava and fire. However, they can take damage from lava as it does not prevent falling damage like water does. Therefore, if they float in place long enough, they can accumulate enough falling damage that they simply die the moment they touch any surface, including land and the bottom of the lake or stream.
 * Zombie Pigmen, prior to the 10th of November 2010 update, would never forgive the player for attacking them. Now after a certain amount of time has passed since an attack, they will become neutral.
 * The skin file has "thx xaphobia" written on it, as a credit by Notch to the skin's original creator, Xaphopia, also known as X__x.
 * When spawned in the real world due to a pig being struck by lightning, fire will appear on Zombie Pigmen at random times but quickly disappear.
 * Zombie Pigmen, as well as Ghasts, are capable of drowning if under water or lava for too long.
 * The green liquid in the Zombie Pigman skin was originally blood red, but was changed due to users expressing a liking for the existing lack of blood anywhere in Minecraft.
 * Oddly enough, when the crosshairs are set on a zombie pigman, the inventory will turn transparent.
 * A direct hit by a Ghast's fireball will cause a Zombie Pigman to run directly towards the Ghast and attempt to attack it. This behavior has only been observed if the Ghast is touching the ground, usually occurring when the Ghast spawns under a low ceiling. This is likely because Zombie Pigmen cannot find a path to an airborne Ghast. Only the Zombie Pigman which was hit by the fireball will attack the Ghast - nearby Zombie Pigmen will not change their behavior.
 * Zombie Pigmen's golden swords never break.
 * Zombie Pigmen were the first (completely [spiders are neutral at day but not at night]) neutral mob in Minecraft.
 * Zombie Pigmen will catch on fire for a short time when hit by lightning, but will not take any damage.
 * Zombie Pigmen were originally previewed as passive creatures with no swords before the Halloween update. After Alpha 1.2, they are neutral to the player and wield gold swords.

Drops

 * 0-3 Cooked Porkchops

Bugs

 * If a Zombie Pigman falls from a height of about 3 blocks and hits you, it will kill you.
 * If a player attacks a zombie pigman on SMP, they turn hostile to ALL players. If the player who attacked them dies or goes away, the zombie pigmen attack the next player who is closest to them.