Thomas Dillon (c. 1535 – 1606) was an Irish judge and landowner: his descendants held the title Baron Clonbrock. He was born at Proudstown, near Navan, County Meath. He was a grandson of Gerald Dillon, whose elder brother Sir Robert Dillon founded the senior branch of the family which held the title Earl of Roscommon. Thomas's father, Richard Dillon, was a High Court judge. He married Alice Shaen, sister of Sir Francis Shaen, ancestor of the Shaen Baronets. They had at least one son Robert (died 1628). Thomas's last direct male descendant Robert Dillon, 5th Baron Clonbrock, died in 1926.