Like Villagers, their undead brethren have a long history in Minecraft. Zombie Villagers before the Village and Pillage update were quite different and went through many changes through each update. While their base concept of just being a Villager that died and now groans in the night with the rest of the undead was the same from the beginning.
This is the version Zombie villagers were first added so it is also the version where they first began spawning. They spawned anywhere normal Zombies could, having a small chance every time a Zombie spawned for it to be a Zombie Villager.
They were also compatible with the Halloween only feature where mobs would spawn with Pumpkins and Jack O’ Lanterns on their heads
Though baby Zombie Villagers were added all the way back in 1.4.2, this is the first version where they could spawn and they spawned just the same way as adult Zombie Villagers did, having a small chance to spawn instead of a normal baby Zombie.
This version added Chicken Jockeys, a rare variant of baby Zombies which makes them ride a Chicken. This functionality extended to baby Zombie Villagers allowing them to spawn as Chicken Jockeys as well.
A new place for Zombie Villagers to spawn was added, making a guaranteed Zombie Villager Priest spawn in the basement of the rare Igloo structure.
This version added more Zombie Villager spawns in rare structures, allowing them to spawn in Abandoned Villages.
This version finally differentiated Zombie Villagers from Zombies. Until now they were exactly the same as Zombies aside from the model they used but now they were considered a different mob and received their own spawn egg, allowing players in Creative Mode to easily spawn them. They also can not longer spawn from Zombie Spawner blocks.
Along with their addition came an ability to transform the Zombie Villager back into a normal Villager by throwing a Potion of Weakness at them and then feeding them a Golden Apple.
This version changed quite a bit. It allowed Zombie Villagers to catch players on fire if they were also on fire when attacking. It added a mechanic where Zombie Villagers, as well as normal Zombies, would call reinforcement Zombies upon being attacked. Finally, it added a mechanic where Zombie Villagers would do more damage the lower their health was, though this mechanic was soon removed.
This version increased the range of Zombie Villager’s sight to 40 blocks and added spawning new Zombies to the calling reinforcement mechanic. In addition to this their AI was changed to make them form hordes more.
This version made Zombie Villagers run away from exploding Creepers, a mechanic which was soon removed.
In this version, when a player wears a Zombie Head, the vision of Zombie Villagers is reduced. Zombie Villagers, as well as Zombies, received an attack animation similar to the one Zombies had all the way back in Minecraft’s Alpha Survival Test versions.
Zombie Villagers now have profession-based clothing and turn into Villager with the corresponding profession when cured.
This version was all about making the Zombie Villager independent from the Zombie and with that, they received their own unique set of sounds.
Zombie Villagers, along with normal Zombies, will trample Turtle Eggs and attack Turtles. And after 10 whole updates, the bug where baby Zombie Villagers did not burn in the sun was finally fixed and they now burn along with the rest of the undead.
Along with their addition, Zombie Villagers and normal Zombies received rare drops of Carrots and Potatoes. Zombie Villagers also drop Rotten Flesh like normal Zombies do.
Items picked up by Zombie Villagers are also dropped on death.
This version allowed baby Zombie Villagers to drop normal Zombie loot and experience.
Zombie Villagers could drop a Zombie Head when killed by a Charged Creeper in this update but this feature was removed in version 1.11 when they were distanced from normal Zombies.
Zombie Villagers had their textures changed a few times, but at first, they simply had a green-looking Villager head on a normal Zombie body as their texture.
Baby Zombie Villagers used to not display items worn on their head properly, having them float above them strangely.
Including baby variants, the new Zombie Villagers have 240 different types covering every biome and profession.
How do I spawn a Zombie Villager in older versions in Creative Mode?
Before 1.11, there was no spawn egg for Zombie Villagers. Instead, the way to spawn them was to just use a Zombie Spawn Egg a ton until one of them spawned as a Zombie Villager.