The trickster god in Norse mythology known for his cunning and shape-shifting abilities is Loki. He is a complex figure, embodying both chaos and cleverness, often causing trouble for the gods while also helping them at times. Loki's transformations and unpredictable nature underscore themes of identity and deception in Norse stories. His actions ultimately lead to significant events, including Ragnarök, the apocalyptic battle in Norse mythology, highlighting his integral role in the mythic narrative.