In mythology, and in the study of folklore and religion, a trickster is a god, goddess, spirit, man, woman, or anthropomorphic animal who plays pranks or otherwise disobeys normal rules and norms of behaviour.
While the trickster crosses various cultural traditions, there are significant differences between tricksters in the traditions of many Indigenous peoples and those in the Euro-American tradition:
"Many native traditions held clowns and tricksters as essential to any contact with the sacred. People could not pray until they had laughed, because laughter opens and frees from rigid preconception. Humans had to have tricksters within the most sacred ceremonies for fear that they forget the sacred comes through upset, reversal, surprise. The trickster in most native traditions is essential to creation, to birth.”
Native tricksters should not be confused with the Euro-American fictional picaro. One of the most important distinctions is that "we can see in the Native American trickster an openness to life's multiplicity and paradoxes largely missing in the modern Euro-American moral tradition".
The boys ran into a trickster in season two. It was punishing people who were, as Dean put it, 'dicks'. He managed to kill two people and traumatize a third before the boys staked him with a wooden stake...or so they thought. As soon as they took off in the Impala, the trickster's 'body' faded away and the real trickster came into view. The trickster Dean had staked had been another illusion. The trickster returns in Mystery Spot, when he tortures Sam with reliving Dean's death over and over again until he finally tells Sam that he's been trying to do it for Sam's own good, realize that he can't save his brother, but he finally just gives up and lets the brothers go.