One of the Islamic State's most feared executioners and propagandists has been killed in a coalition airstrike in Iraq, the Pentagon said on Monday.

Abu Waheeb, who starred in a series of chilling execution videos, was almost unique among Isil terrorists for his willingness to appear in propaganda films without wearing a mask to disguise his identity.

He featured in dozens of Isil publicity releases, grinning for the cameras as he went about his work, and until the arrival of "Jihadi John" in late 2014, was one of the terror group's most notorious figures.