Tadhg Ó Caiside (d. 1450), was a Gaelic-Irish physician and Chief of the Name.
Ó Caiside was a member of a brehon family based in what is now County Fermanagh. His great-great grandfather was Gilla na nAingel Ó Caiside (died 1335), and may in turn have been a descendant of the 12th-century poet, Gilla Mo Dutu Úa Caiside.
The Annals of Ulster record Tadhg's death, sub anno 1450: