His father was the younger brother of Thomas Butler, 1st Baron Cahir of the first creation.

[3] His father, Piers Butler, felt that he was oppressed by Ormond and sided in 1565 with Gerald FitzGerald, 14th Earl of Desmond fighting on the losing side against the Ormonds in the Battle of Affane.

Theobald and Mary had six sons: —and two or three daughters: In 1567 Butler was knighted at Clonmel by Henry Sidney,[17][18] who had been appointed lord deputy of Ireland in 1565.

When Butler's first cousin Edmund, the 2nd Baron, died without issue in 1560, the title became extinct.

[20] He became the 1st Baron Cahir (of the second creation) and ruled much of the barony of Iffa and Offa West.