In the fictional utopian nation of Yuldo, established by the righteous bandit hero Hong Gil-dong, Jeon Woo-chi is a dosa, a Taoist wizard, who gained his powers by swallowing a gumiho fox bead. A friend's betrayal causes him to lose his mentor, and sorcery turns the love of his life Hong Mu-yeon into an emotionless assassin. So in order to avenge them, he travels to Joseon, and is moved by the plight of the people and becomes a reluctant hero to them.
Cha Tae-hyun as Jeon Woo-chi / Lee Chi, a mischievous, confident wizard who's always chasing women. He doesn't seem like he amounts to much, but that's all an act; he just adopts that persona so that people will underestimate him. He lives a cover life as Lee Chi, a wimpy reporter for the local newspaper who runs away at the first sign of trouble. Though he only cares about his own revenge mission, Woo-chi keeps getting entangled in the citizens’ problems. He finds it all annoying, but the more he helps, the more they start to see him as a hero. It's the last thing he wants, but perhaps a fate he can't avoid.[5]
Uee as Hong Mu-yeon, Hong Gil-dong's granddaughter, princess of Yuldo. She learned wizardry along with Woo-chi, and is brave and strong-willed, and doesn't flinch in the face of death. Ma Sook puts her under a spell that erases her memory and controls her mind, taking her away to use her as a weapon against the Joseon people. But once a month, the energy from the Moon weakens the spell, and she remembers and longs for Woo-chi.[6][7][8][9][10][11][12]
Lee Hee-joon as Ma Kang-rim, Woo-chi's nemesis. He grew up with both Mu-yeon and Woo-chi in Yuldo. Kang-rim loved Mu-yeon, but always ended up second best in everything, including winning her heart. He chooses to betray them, setting the story in motion.
Baek Jin-hee as Lee Hye-ryung, who is searching for her brother Lee Chi. Lee Chi's been missing for some time, so when Woo-chi takes on his identity, Hye-ryung thinks she's found her long-lost oppa after all this time. Now he has to keep her fooled and thinking that he's her brother, when he's really not.
Kim Kap-soo as Ma Sook, a powerful wizard and Kang-rim's uncle. He was once a follower of Hong Gil-dong and part of the group Hwalbindang, but has betrayed Yuldo and set his sights to loftier kingdoms: He wants to conquer Joseon.[13]
Sung Dong-il as Bong-goo, a slave of Saboksi who later becomes Jeon Woo-chi's loyal servant.[13]
Lee Byung-joon as Woon-bo, Lee Hye-ryung's servant/guardian, a quack guru/fortune teller.
Ahn Yong-joon as Yi Geo, who ascended to the throne at a young age as the result of a coup to dethrone his half-brother the king. He once feigned utter indifference in politics as a mode of self-preservation, and even after becoming king he isn't quite able to command full authority and continues the pretending game: he has three facades he hides behind—weak, lax, and indecisive. In actuality, though, Yi Geo harbors "a grand vision for a new Joseon."
Hong Jong-hyun as Seo Chan-hwi, a member of the royal guard. He is a humorless, rule-following man of honor, and keeps trying to catch Woo-chi because he's acting outside the law.[14]
Lee Joo-yeon as Eun-woo, a damo ("female officer") who's a skilled warrior and royal guard.