Gwi is the major antagonist in 2015 South Korean television series Scholar Who Walks the Night. Gwi is a centuries old vampire who lives in a dungeon within the royal palace, the Underground Palace, and works with the prime minster who has always sought power against the King. Gwi was indirectly responsible for making the Prince's good friend Kim Sung-yeol a vampire and is also the murderer of Sung-yeol's fiancee, Myung-hee. He rules over the king, whose ancestors needed Gwi's assistance in the creation of Joseon. He launched a coup against the king and became king himself.
Gwi was a cruel and sadistic vampire who enjoyed his victims suffering or turning them into vampire servants. He also murdered members of the royal family including the Queen of Joseon. Crown Prince Junghyun and his best friend Kim Sung-yeol began writing books about a vampire who drank the blood of the King's concubines. After the Crown Prince's death, Kim Sung-yeol got bitten by a guardian vampire and turned into one himself. Since then, he's been trying to kill Gwi. He's his biggest enemy. 120 years later, a girl called Hye-ryeong is the human who's closest to him because she had to serve him since she was 10 years old. After her death, Gwi realises that he wanted to keep her by his side forever and that he had feelings for her. Gwi already had a human lover in the past, but he killed her because she gave birth to his child. A child of a vampire and a human can kill a vampire, so he tried to kill every remaining human of his bloodline.
The reason for Gwi's hate against humans is that he failed to keep his human heart and his feelings after turning into a vampire. He secretly wishes to become a human again.
It is not known how he became a vampire.