Introduction
Ahiravana is a sorcerer king of Patala, the netherworld. He appears in later Ramayana traditions, including the Krittibas Ramayana, and not in Valmiki.
This article follows later traditions.
The kidnapping
In these versions, Ahiravana, an ally or relative of Ravana, kidnapped Rama and Lakshmana at night while they slept and took them to Patala to sacrifice them to the goddess. Hanuman followed and defeated him, taking the form of Panchamukhi Hanuman, the five-faced Hanuman.
Relationship to Ravana
Accounts differ on whether he was Ravana's brother, son or an unrelated Patala king.