Hethum I (died 1271) (also transliterated Hethoum, Hetoum, Het'um, or Hayton) rules the Armenian Kingdom of Cilicia (also known as "Little Armenia") from 1226 to 1270.

He is the son of Constantine, Lord of Baberon and Partzapert (a third-cousin of Leo I) and is the founder of the dynasty which bears his name: the Hetoumids.

Due to diplomatic relations with the Mongol Empire, Hethum himself travels to the Mongol court in Karakorum, Mongolia, which is recorded in the famous account "The Journey of Haithon, King of Little Armenia, To Mongolia and Back" by Hetoum's companion, the Armenian historian Kirakos Gandzaketsi.