Kirmira was a Rakshasa, the brother of Bakasura, and a good friend of Hidimba. He lived in the forest of Kamyaka, and used to terrorize the Rishis who inhabited that forest. He ran into the Pandavas when they began their exile in the Kamyaka forest. Upon learning that Bhima was present, who had slain his brother Bakasura, the Rakshasa then challenged the Pandava to fight. After a fierce battle, Bhima choked Kirmira to death. (Mahabharata, Book III: Varna Parva, Section 11).