Abu Said Uthman I (Arabic: أبو سعيد عثمان الأول), or Othmane ibn Yaghmurasen or in Algerian Arabic ( أبو سعيد عثمان الأول, Abu Sa'id Othman āl-awel), ruled the Zenata Berber Kingdom of Tlemcen (in modern day Algeria) from March 1283 to June 1304.
Abu Said Uthman I succeeded his father Yaghmurasen ibn Zayan (reigned 1236–1283) as ruler of the Zayyanid dynasty.
Through marriages with the Hafsids, he was able to establish good relations with his eastern neighbours.
Only under his successor Abu Zayyan I (reigned 1304-1308) did the Marinids withdraw back to Al-Maghrib (al-Aqsa) following the death of their Sultan and the subsequent dynastic infighting weakened their power.
Abu Said Uthman I led many military actions designed to consolidate his power and strengthen his position against his rivals (mainly the Marinids).