The odd spirit is a baboon entity who often meditates near the Realm of Koh in the Spirit World. He is one of many strange looking spirits that dwell near this realm and speaks with a distinct accent. Very irritable, he greatly dislikes being disrupted during meditation.
When Aang arrived in the Spirit World seeking advice on how to defeat the Fire Nation that was attacking the Northern Water Tribe, he asked the odd spirit for help, but the spirit wanted him to leave. Aang kept persisting for the cranky spirit to help him, but the odd spirit only grew more agitated as he tried to continue his meditation. When Aang was still hanging around, the spirit told him to follow a ball of light and remarked, "Finally!" when he left. After losing the light, Aang was advised by AvatarRoku to see Koh, the Face Stealer. After Aang came back from his encounter with Koh, Hei Bai helped him return to the mortal world. The odd spirit remarked, "Good riddance!" much to the annoyance of Hei Bai, who transformed into his monstrous form and struck the odd spirit with a huge energy blast, sending him flying.
The odd spirit directed Aang to Avatar Kuruk on Aang's second adventure through the Spirit World, although Aang does not remember it.
The odd spirit always prefers tranquility to aid him in his meditation and hates to be disturbed. If someone disrupts this serenity, the spirit will attempt to ignore them and remain unhelpful in order to continue with his meditation. This quality was shown when Aang entered the Spirit World, attempting to locate the identity of the Moon and Ocean Spirits; Aang turned to the odd spirit for help, but the spirit simply brushed off his request and attempted to return to his meditation. When Aang finally left, the spirit felt relieved.
Although the odd spirit's voice actor is not listed in the ending credits of "The Siege of the North, Part 2", the creators mention during the DVD audio commentary for the episode that he is voiced by Mark Hamill.