Had a weird group that had "bod-e-man," that were amorphous humanoid beings with 1 HP and could not attack in any way. The PCs could just pick them up and they would periodically die off. They served no real purpose, except to ignore encumbrance. Of course players, being players, starting figuring out ways to use them to great advantage without them ever officially making an "attack." For example, the tinker gnome made the equivalent of a steamroller that could be driven by a bod-e-man because avoiding the damage was a saving throw, not an attack. When we got a lot of them, they became "trapfinders," leading the party down into the dungeons. The DM greatly regretted the incorporation of the bod-e-man, but his brother adamantly forced him to keep them for the campaign (this was in high school).