Kayqubad I or Alā ad-Dīn Kayqubād bin Kaykhusraw (; , 1190–1237) was the Seljuq Sultan of Rûm who reigned from 1220 to 1237. He expanded the borders of the sultanate at the expense of his neighbors, particularly the Mengujek Beylik and the Ayyubids, and established a Seljuq presence on the Mediterranean with his acquisition of the port of Kalon Oros, later renamed Ala'iyya in his honor. The sultan, sometimes styled "Kayqubad the Great", is remembered today for his rich architectural legacy and the brilliant court culture that flourished under his reign.