Ala ud-Din Timurtash (died 1328; also Temürtaš or Timür-Tash, Turkish: Alaeddin Demirtaş) was a member of the Chobanids who dominated politics in the final years of the Ilkhanate.

He was born to Mongol emir and general Chupan as his second son c. 1298. Timurtash was mentioned for the first time in a hunting party organized by Öljaitü in 1313 where almost all Chupanids participated. He lived with his father until 1314 in Sultaniyeh.

He was appointed to Mongol viceroyalty of Anatolia by Chupan after Keraite emir Irinjin was recalled to Diyar Bakir in 1314. His deputy was Sinaneddin Ariz (or Seyfeddin Razi), while his vizier tasked with collection of the provincial revenues was Jalal al-Din, son of Rashid al-Din Hamadani. However, when Irinjin rebelled in 1319, his lands were pillaged by Keraites, Timurtash himself fleeing to Danishmendid territory. He was reconfirmed as viceroy after the victory of Chupan. However, this revolt made Timurtash unsure of his position and forced him to ally with Mamluks, even to the point of sending a letter to the Sultan to accept him as a governor.

His tenure was marked by the suppression of vassals of Ilkhanate, namely the Armenian Kingdom of Cilicia and the Anatolian beyliks. He succeeded in capturing Konya in 1320 from Karamanids and marched on Leo IV in alliance with al-Nasir Muhammad in 1321 and captured Ayas on 10 May according to Abulfeda. He also sacked Christian centers of Kayseri and Erzurum, forcing inhabitants to convert to Islam.

Timurtash implemented policies inspired by the writings of Sufi scholar Ibn Arabi, making it mandatory for non-Muslims to wear conical hats with yellow turbans as to distinguish them from Muslims, for "it would exalt Islam and abase the infidel".

Growing rebellious every year, he declared open revolt against Abu Sa'id in December 1322 - January 1323, calling himself 'Sahib-az Zaman' (Arabic: صَاحِب ٱلزَّمَان, lit. 'Master of the Era') and 'Şah-i İslam' (Emperor of Islam) minting coins with his new title Mahdi. He banned alcoholic drinks and reforged an alliance with the Bahri Mamluks, forcing Chupan to march against his son in 1324. Chupan convinced his son to surrender and executed chief qadi of Anatolia Najm al-Din Tashti and emir Surkaji as rebellion instigators. He then secured a pardon for Timurtash and even had him reinstated as viceroy of Rum.

As soon as his reappointment, he marched on the Anatolian beyliks, captured Beyşehir, capital of the Eshrefids, executing their bey Süleyman II by drowning him in Lake Beyşehir on 9 October 1326, annexing it to the viceroyalty. Later he marched on Dündar of Hamidoğlu who fled to Alanya, but Timurtash caught up and executed him as well. He attacked Turgutids, Germiyanids and Beylik of Tadjeddin as well. He sent his subordinate Eretna against Nasir-ud Din Ahmed of Sahib Ataids in August 1327, capturing Karahisar, while bey fled to Yakup I of Germiyan. According to Faruk Sümer, he executed at least nine Seljukid princes, possibly trying to create his own sultanate.

Upon learning of his brother Demasq Kaja's execution on 24 August, Timurtash ended his campaigns and returned to Kayseri, then Sivas, recalling Eretna as well. Receiving news of Chupan's execution in October, he contemplated to submit to the Ilkhan, but nevertheless left for Larende on 22 December 1327 and then to Egypt, leaving Eretna as acting viceroy. He was replaced by Amir Muhammad from Oirat tribe, an uncle of Abu Sa'id.