Pak Yà Ânggyu () was a Korean general who served Later Paekche. He was the son-in-law of its king, having married Kyà Ân Hwà Ân's daughter. When Kyà Ân Hwà Ân escaped to the rival kingdom of Goryeo after being overthrown by his son, Pak also defected to Goryeo. Pak was the father of Lady Dongsanwon, Queen Mungong, and Queen Munseong.
In March 935, Pak Yà Ânggyu's father-in-law, Kyà Ân Hwà Ân was overthrown in a palace coup and imprisoned at Geumsansa Temple () by his oldest son, Kyà Ân Sin'gà Âm, then in June, Kyà Ân Hwà Ân escaped and fled to Goryeo. In September 936, after secretly discussing and consulting with his wife, Princess Kyà Ân Aebok, Pak sent an envoy to Goryeo to express his intention to defect and said that he would welcome the Goryeo army. Goryeo's king, Wang Kà Ân, then rejoiced greatly about this and treated that messenger generously and sent him back to Pak. Later, when Wang Kà Ân finally won in attacked the Later Paekche, Pak helped to contribute to the unification of Later Three Kingdoms.
After this, Wang Kà Ân rewarded Pak Yonggyu with land of an area of 1,000 kyà Âng (). Wang Kà Ân also granted Pak's wife with 35 horses () and gave their two sons government posts. Due to Pak's contribution in helping Wang establish the new Goryeo Dynasty, Pak became officially titled as one of the Threefold Great Rectifers (), along with Yu Ch'à Ân'gung and Hwangbo Che-gong.
Since Pak was the one of Threefold Great Rectifers, both him and his wife had a good relationship with Taejo of Goryeo, they regarded and treated each other like siblings. Because of this too, Pak's oldest daughter became 17th wife of Taejo and his other two daughters became the first and second wives of Taejo's son, Jeongjong of Goryeo.