Several Korean dramas feature male leads who start as antagonists or have villainous traits, but eventually fall in love with the female lead, leading to a transformation or redemption. One I can think of is Mr. Sunshine and Vincenzo.
Mr. Sunshine:
Go Dong Mae, a complex character with a dark past and violent tendencies, finds himself drawn to and eventually falling for the female lead.
Vincenzo:
While not the primary romantic interest, the character Jang Joon-woo (portrayed by Ok Taecyeon) starts as a seemingly harmless intern but is later revealed to be the ruthless villain who develops an obsession with the female lead.
