Thomas Butler, 2nd Baron Cahir (before 1568 – 31 January 1626/27) was an Anglo-Irish peer.
He was the son of Theobald Butler, 1st Baron Cahir and Mary Cusack.
They had a daughter, As this marriage was also without male issue, the barony devolved upon his nephew Thomas who was the third son of the baron's uncle, Piers Butler.
His widow remarried Sir Thomas Esmonde, 1st Baronet and had further issue.
During the siege Thomas was held prisoner, although his wife and brother refused to give up the castle.