What was the Norse god Odin's enemies?

Odin, the chief god in Norse mythology, had several notable enemies, including the giantess Angerboda, who bore him monstrous offspring like Fenrir the wolf and Jörmungandr the Midgard Serpent. He also contended with the frost giants, particularly their leader, Ymir, who represented chaos and destruction. Additionally, Odin faced antagonism from Loki, his former ally, who ultimately betrayed him and assisted in bringing about Ragnarok, the end of the world. These conflicts highlight the complex relationships and themes of fate and power within Norse mythology.