In Ark: Survival Evolved, creatures can have various hitboxes that modify damage when hit. 37 creatures have head hitboxes, meaning a headshot will deal significantly more damage and torpor (for most creatures, 3 times more).
Only 25% of creatures (37 of 148) have headshot modifiers. Note that this list only includes tamable creatures (with the exception of the Titanoboa.)
All flying creatures have 3× headshots, besides the Onyc.
Swimming creatures do not have headshots or any other modifiers.