Scenario 47: Replacing Dead Head With Body Token?
You do not replace the Ouroboros head with a body token

During a Haunt, special actions are explicitly given in the following books:


Secrets of Survival (read by the Heroes)
Traitor's Tome (read by the Traitor)


According to the Traitor's Tome, the Ouroboros head only leaves behind a body token on movement, and only if there isn't already a body token in the room it just left. Since neither the Traitor's Tome nor the Secrets of Survival state that anything happens when an Ouroboros head is killed (outside of the Survivors winning if both are killed), it is not replaced with a body token on death.