Terence O'Dempsey served as sheriff of Queen's County, and was knighted by Robert Devereux, 2nd Earl of Essex in 1599.
His third wife was Margaret Whittie, widow of John Ichingham (died 1616) of Dunbrody, County Wexford;[1] by her first husband she had a daughter Martha, who married Lewis, Terence's grandson and heir.
He conformed at least outwardly to the Church of Ireland, although his second wife Genet was a devout Roman Catholic, as were her children by her first husband John Bathe: two of his sons became priests.
His daughter Eleanor married Peter Sarsfield of Tully Castle in County Kildare, a member of a wealthy Old English family.
[2] She was the grandmother of Patrick Sarsfield, the leading Jacobite general during the Williamite War in Ireland.