The O'Donnell clan is a prominent Irish family with roots in County Donegal. Historically, they were one of the leading Gaelic families in Ireland, particularly during the late medieval period. The clan's influence peaked when they ruled as the O'Donnell dynasty, with their territory known as Tir Chonaill. The O'Donnells were known for their resistance against English rule and played significant roles in various conflicts, including the Nine Years' War. Their legacy includes notable figures such as Hugh O'Donnell, who was a key leader during this period. Today, the O'Donnell name remains common in Ireland and among the Irish diaspora.