Minecraft wiki entry for Sitting, associated text: Zombies, husks, drowned, skeletons, strays, wither skeletons, illagers (vindicators, pillagers, evokers, illusioners‌[Java Edition only]), piglins, zombified piglins and endermen can also enter the sitting animation, which appears similar to the player's. In addition, spider jockeys, chicken jockeys, and skeleton horsemen also include sitting mobs. Any humanoid monster summoned riding another mob appears sitting.