Ghias ad-din (fl. 1206–1226) was a member of the Seljuq dynasty of Rum and husband of Queen Rusudan of Georgia from c. 1223 to 1226. A son of the emir of Erzurum, he converted to Christianity on his father's order so as he could marry the queen of Georgia. Ghias ad-din's position at the Georgian court was weak and the spousal relationship was strained due to Rusudan's unfaithfulness. He shifted back and forth across the religious and political divide during the Khwarezmid invasion of Georgia in 1226. Around the same time, he was repudiated by Rusudan, and thereafter disappears from records, leaving two children behind, a daughter, Tamar, and a son, David.