Witch

Witches are hostile, ranged mobs commonly spawning in Swamp Huts. They're the second hostile ranged mobs to spawn in the Overworld - the first being the skeleton.

Appearance
Witches have a similar appearance to the villager mob, and they wear purple and green robes with brown leggings underneath. They have large noses (which moves slowly around on the Witch's face, as stated in Dinnerbone's tweet) with a single wart and have lavender colored eyes. They wear a stereotypical witch hat with a green buckle on it, and their skin is slightly paler than the normal villager. However, witches periodically give off purple star particles similar to the villager's green stars.

Minecraft witch! 

Combat
The witch mob uses splash potions of poison, weakness, damage, and slowness to fight the player. The current order of potions thrown is; slowness, poison, they will then proceed to throw potions of harming until the player is no longer poisoned which they will rectify by throwing another splash potion of poison and will continue to do this. The splash potion of harming will occasionally be substituted by potions of slowness. These potions will affect other mobs - not just the player. The witch does not burn in sunlight and when set on fire, drinks a potion of fire resistance. This can be seen when a bottle appears in the witch's hands. Iron Golems will attack witches as most other hostile mobs.

Witches are immune to splash potions of poison, slowness, and instant damage. When damaged, they will drink potion of regeneration, healing themselves. When drinking a potion, a witch's nose will point straight forward (instead of down). While healing they can't attack the player. If lit on fire by lava or fire, witches will quickly drink potions of fire resistance, making lava and fire ineffective ways of killing witches.

A bow will likely be the best weapon for dealing with a witch, as the splash potions have only a short range (at most nine blocks) compared to arrows (which, when fired straight at full charge, travel 24 blocks). If a bow is not an option, however, a direct melee charge is the best option. Due to the Witch's slow attack speed, if the player runs in a straight line and manages to get a quick sword strike in, the Witch will try to heal themselves with a potion of regeneration, leaving the player to attack them without fear of retaliation.

Upon death, witches rarely drop potions of healing, swiftness, and fire resistance.

Bugs

 * If a witch gets stuck in a wall, then it will not die.
 * When a witch drinks a potion, the bottle will not show the drinking animation; only the bottle itself.

Trivia

 * If a witch shoots another witch with a potion, the witch who is hit will become angry but will not kill the other witch; instead, it will hit the offending witch once with a potion.
 * Though it's not actually a villager, the witch's skin is found in the Villager folder in minecraft.jar.
 * Witches have more mob drops than any other mob in the game.
 * Witches have the most health of any normally aggressive mob other than boss mobs. However, maximum-sized Magma Cubes may take more hits to kill due to their high armor value, and may also spawn numerous smaller versions whose collective health combined with that of their full-sized progenitor is well over that of one witch.
 * Witches are the only non-boss mob to naturally regenerate health.
 * Unlike villagers, witches do despawn when the player is out of range since they are hostile mobs.
 * Witch Huts are similar to the hut of Baba Yaga (a famous witch in Slavic folklore) that stood on chicken legs.