Wang Ja, Duke Gangyang

Wang Ja, enfeoffed as Duke Gangyang (died 1308), was the eldest son of King Chungnyeol of Goryeo by his first consort. Although the eldest son, he was barred from succession because his half-brother Chungseon was born to Qutugh Kelmysh, a daughter of Kublai Khan.

Sent to Dongsimsa temple in 1279, he was recalled only in 1283 and enfeoffed as Duke Gangyang. His sons included Wang Ko, Prince Yeonan. He died in 1308; in 1391 his great-grandson, King Gongyang, gave him the posthumous name Jeonggang.