Tir Ollíol

{{Use dmy dates|date=April 2022}}

{{infobox historic subdivision

| Name = Tir Ollíol

| subdivision_type = Túath/ Tríocha Céad

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| End = 1603

| Replace = Barony of Tirerill

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| Status = Túath (Territory)

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| membership_title1 = Confederation

| membership1 = Iochtar Connacht

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Tir Ollíol was a túath in northwest Ireland. It was part of the confederation of Iochtar Connacht until the late 16th century.{{cite web|author=@irishcentral |url=http://www.irishcentral.com/roots/travel/county-sligo-87161952-237687501.html |title=What's your Irish County? County Sligo |publisher=IrishCentral.com |date= |accessdate=2014-04-25}} Its name is preserved by the barony of Tirerril in southeast County Sligo. It is named after Olliol, one of the sons of Eochaid Mugmedon and half brother of Niall of the Nine Hostages, from whom descended the Uí Ailello, a branch of the early Irish dynasty known as the Connachta.