Bandit and zombie illagers.

The bandit is an illager that can spawn in raids with a variety of weapons, (Sword, axe, bow, etc.) they will go into villager houses and steal from the chests. Bandits can also spawn in abandoned camps or naturally.

Zombie illagers are when a zombie kills an illager. If there was a zombifying problem in the woodland mansions though, the rooms would probaly need torches.