King Hyogong of Silla (Hangul/Hanja: 효공왕/孝恭王; Born: 883 - Died: 912; Reigned: 897–912), whose born as Kim Yo (김요/金嶢) was the 52nd ruler of the Korean kingdom of Silla. He was the illegitimate son of King Heongang by Queen Dowager Uimyeong (의명왕태후/義明王太后). He married the daughter of Ichan Ugyeom.
His reign saw the expansion of Later Three Kingdoms powers, HuGoguryeo-Taebong which led by Gung Ye and HuBaekje which led by Gyeon Hwon across what had once been the western marches of Unified Silla. In 905, Silla lost its holdings to the northeast of Jungnyeong Pass (죽령) in the present-day Yeongju City and Danyang County. In 907, Gyeon Hwon's HuBaekje forces seized ten castles to the south of Ilseon.
Faced with these defeats, the king turned to drink and neglected state affairs. Upon his death in 912, he was buried to the north of Sajasa temple with its specific location at Baeban-dong san 14-beonji, Gyeongju City, Northern Gyeongsang.