Tadhg Caech Ó Cellaigh was a King of Ui Maine within Ireland, who retired in 1476.
Upon the death of Aedh na gCailleach Ó Cellaigh in 1469, the Ui Maine elected two kings, ruling Iar Ui Maine (west) and Airthir Ui Maine (east) respectively.
They were Tadhg Caech Ó Cellaigh of Airthir, and William Ó Cellaigh in the west.
Upon the retirement of Tadhg in 1476, Uilliam became king of all Ui Maine, installing his brother, Donnchadh, as tánaiste in Airthir.
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