'Humanoid' is a category of mobs used by certain spells, skills and discs. For example, rangers can obtain the passive AA Headshot, which allows them to randomly hit a humanoid for 32,000 damage.
Known 'humanoids' include:
Crawlers, golems, and arachnae in PoV
Giants in PoS
Goblins in nurga
Humans in FPE and FPW