Uijo of Goryeo
King Uijo of Goryeo was grandfather of Taejo of Goryeo.
His temple name was Uijo.
Posthumous name was the great Gyeonggang.
Gang Bo Yuk
Gang Bo Yuk was the maternal grandfather of first King of Goryeo, Taejo of Goryeo.
Seongjong of Goryeo
Seongjong of Goryeo( 15 January 961 – 29 November 997)( r. 981–997) was the sixth ruler of the medieval Korean kingdom of Goryeo.
Myeongjong of Goryeo
King Myeongjong (8 November 1131 – 3 December 1202) (r. 1170–1197) was monarch of the Goryeo dynasty of Korea.
He was the third son of King Injong.
Although it was intended that Injong's second son should succeed his father, he was assassinated because Jeong Jung-bu feared that he might become a threat to him in the future.
Myeongjong was a weak king, and was merely on the throne to show the general populace they still had a king, as the true rulers were the military leaders.
His reign saw constant bloodshed as well as the deaths of the rebels Chung Jung-bu, Yi Ui-bang, and Yi Ui-min (not related to Yi Ui-Bang)
but also the hero, Gyeong Dae-seung
(General Gyeong was in fact the most loyal of the military leaders.
Yet Myeongjong hated and mistrusted him because of his popularity with the populace).
After twenty-seven years on the throne, he was sent into exile by the military ruler of the time, Choe Chung-heon, and Injong's fifth son, King Sinjong, was placed on the throne.
Consorts:
Queen Janghwa
Queen Janghwa(? – 934 or 943) was the second wife of Taejo of Goryeo and the mother of Hyejong of Goryeo who was the second king of Goryeo.
Gangjong of Goryeo
Gangjong (10 May 1152–26 August 1213)
(r. 1211–1213) was the 22nd ruler of the Goryeo dynasty of Korea.
He was the eldest son of King Myeongjong.
His mother was Queen Gwangjeong, a Kim, and his wife was Queen Wondeok, a Yu and the daughter of Sin An-hu.
Gangjong was confirmed as heir in 1173.
In 1197, he and his father were driven to Ganghwado by the military leader Choe Chung-heon.
In 1210 Gangjong returned to the capital, and he was given a royal title by Huijong in the following year.
After Choe drove Huijong from power that year, Gangjong was placed on the throne.
Gangjong's tomb is located outside the old Goryeo capital, in modern-day Hyŏnhwa-ri, Kaepung-gun, Hwanghaenam-do, North Korea.
Consorts:
Hyejong of Goryeo
Hyejong of Goryeo( 912 – 23 October 945)( r. 943–945) was the second King of Goryeo.
He was preceded by King Taejo and succeeded by Jeongjong, 3rd Monarch of Goryeo.
Princess Deongnyeong
Princess Deoknyeong(? – 1375) was a Mongolian princess, queen of Goryeo by marriage to Chunghye of Goryeo.
Following her husband's deposition in 1344, she served as regent for her son from 1344 to 1348.
She was from the Borjigin clan and the wife of king Chunghye of Goryeo.
Gukjo of Goryeo
Gukjo of Goryeo  nominated Wang Yung as Sejo of Goryeo and Jakjaegeon as Uijo of Goryeo.
For Gukjo, there are some stories.
His posthumous name was the great Wondeog .
Queen Gongwon
Queen Gongwon( 18 July 1298 – January 1380) also known as Queen Mother Myeongdeok was queen consort to king Chungsuk of Goryeo and the mother of king Chunghye of Goryeo and king Gongmin of Goryeo.
She was from the Namyang Hong clan.

Question: Who is the paternal grandfather of Gangjong Of Goryeo?
Answer: Injong