Butler, Piers (d. 1660?), 1st Viscount Ikerrin , confederate commander in Munster, was the son of Sir James Butler, Baron Ikerrin, of Lismallon, Co. Tipperary, and his wife, Elizabeth, daughter of Thomas Butler (qv), 10th earl of Ormond. He married Ellen, daughter of Walter Butler (qv), 11th earl of Ormond, and lived at Lismallon, owning extensive properties in the baronies of Ikerrin, Eliogarty, Slieverdagh and Campey, and Lower Ormond. Butler was created Viscount Ikerrin in May 1629. He sat in the house of lords in 1635 and was a member of the lords’ committee on privileges and grievances in 1640–41. On the outbreak of the rebellion in 1641 he defended his tenants against attacks by the insurgents, but subsequently took up arms himself. He brought Munster forces to the assistance of the Leinster army, and at the battle of Knockateriff he and James Tuchet (qv), earl of Castlehaven, engaged and were defeated by forces commanded by Sir Charles Coote (qv) and James Butler (qv), 12th earl of Ormond. The decision to fight was taken against the wishes of the other Irish commanders.
Ikerrin then accompanied Richard Butler (qv), 3rd Viscount Mountgarret, through Tipperary and Cork and participated in the battles of Liscarroll, Kilrush, and Ross, and the sieges of Limerick castle, Ballinakill, and Borris. He was among those requesting assistance from Ulick Burke (qv), 5th earl of Clanricarde, in June 1642. He attended the confederate general assemblies in 1644, 1647, and 1648–9, and was host to the earl of Glamorgan in March 1646. Later that year he sided with the papal nuncio, GianBattista Rinuccini (qv), in rejecting the first Ormond peace. He was among those who nominated the earl of Glamorgan (qv) general of the Munster forces, and his second son, Richard, was appointed lieutenant general of that army. Ikerrin's name does not appear among those opposing Rinuccini's censure of adherents to the Inchiquin truce in May 1648, suggesting that he continued to support the nuncio.
After the surrender of the Leinster forces in May 1650, Ikerrin returned to Lismallon, and was included in parliament's decree of confiscation in August of that year. He remained as a tenant at will to the state until he received orders to transplant in October 1653. He presented his particulars to the commissioners of revenue in January 1654, declaring seventeen persons who would accompany him to Connacht, 16 acres of winter corn, twenty-four sheep, five cart horses, four cows, and two swine. Before 1 May 1654 he obtained permission to go to Bath for six months to recover from an illness, while his wife was dispensed from transplantation for two months. He returned to Dublin impoverished and was paid £20 by the authorities there on 27 November 1654. He continued to evade transplantation, and in 1656 made contact with Oliver Cromwell (qv), who was sympathetic to his case. Referring to his extreme poverty, Cromwell gave him relief and ordered that he be allowed to retain some of his estate and not forced to transplant. Butler failed to recover Lismallon, which passed to the army, but was not forced to go to Connacht, though he had been allocated lands there. His subsequent fate is unclear, but his will dated 1 March 1660 ordered that he be buried at Kilcooley Abbey, Co. Tipperary.
Ikerrin's eldest son, James, died prematurely in London in 1636, leaving a son, Piers's grandson and namesake. This Piers Butler became 2nd Viscount Ikerrin; he was decreed an innocent protestant, and thereby was entitled to recover his grandfather's estates in September 1670. In 1748 Piers Butler's descendant, Somerset Hamilton Butler, 7th Viscount Ikerrin, was made earl of Carrick by George II.