In Norse mythology, who was represented as the companion of the great gods Odin and Thor?

Loki, in Norse mythology, a cunning trickster who had the ability to change his shape and sex. Although his father was the giant Fárbauti, he was included among the Aesir (a tribe of gods). Loki was represented as the companion of the great gods Odin and Thor, helping them with his clever plans but sometimes causing embarrassment and difficulty for them and himself. He also appeared as the enemy of the gods, entering their banquet uninvited and demanding their drink. He was the principal cause of the death of the god Balder. Loki was bound to a rock (by the entrails of one or more of his sons, according to some sources) as punishment, thus in many ways resembling the Greek figures Prometheus and Tantalus. Also like Prometheus, Loki is considered a god of fire.