Kaykaus I or Izz ud-Din Kaykaus ibn Kaykhusraw was the Sultan of Rum from 1211 until his death in 1220. He was the eldest son of Kaykhusraw I.

The Sultanate of Rûm was a culturally Turco-Persian Sunni Muslim state, established over conquered Byzantine territories and peoples (Rûm) of Anatolia by the Seljuk Turks following their entry into Anatolia after the Battle of Manzikert (1071). The name Rûm was a synonym for the medieval Eastern Roman Empire and its peoples, as it remains in modern Turkish. The name is derived from the Aramaic (rhōmī) and Parthian (frwm) names for ancient Rome, via the Greek Ῥωμαῖοι (Romaioi).