Tomás Ó Caiside, aka An Caisideach Bán, c. 1709 - 1773?, was an Irish friar, soldier, and poet.
Ó Caiside's family were of Ulster stock, his parents settleing in Leacht na Drisheacain (Drishacaun townland, parish of Kilmurry, Castleplunkett, County Roscommon). What is known of his life is told in Eachtra Thomais Ui Chaiside, (The Adventures of Tomás Ó Caiside) which he wrote himself. Two surviving copies, one by his friend and contemporary, Brian Ó Farrell, are kept respectively in the Royal Irish Academy and the British Museum.
He was dismissed from the friary of Ballyhaunis on account of a bad senseless marriage and spent the rest of his life travelling all over Ireland and Britain, as well as central Europe In 1733 he served in the Duke of Berwick's regiment, and was later been pressed into the army of Frederick the Great, where he encountered the Potsdam Giants.
He mentions been in places such as the Palatinate; the Black Forest; Sandhausen; Hanover; Prussia; Brunswick; Bristol; Bideford.
His poems include: