Nizamettin Yağıbasan, or simply Yağıbasan (meaning "enemy raider" or "smashing the enemy") was the sixth ruler of Danishmendids and the uncle of Melik Zünnun.

After Alp Arslan of Seljukids defeated the Byzantine army in the battle of Manzikert in 1071, a series of Turkmen beyliks (principalities) were formed in Anatolia before Anatolia was united by the Sultanate of Rum.

[2] After a further partition by a third brother in Malatya, the Danishment power began to decline.

Mesut I of the Seljuks saw his chance to end the Danishmend dominance in Anatolia.

Yağıbasan allied himself with the other Danishmend rulers and attacked Kılıç Arslan to gain the former status of the beylik.