Simon Atumano (Greek: Σίμων ὁ Ἀτουμάνος) was the Bishop of Gerace in Calabria from 23 June 1348 until 1366 and the Latin Archbishop of Thebes thereafter until 1380.
He lost 1,500 florins of revenue from Thebes and lived thereafter in poverty "more acceptable in the sight of God," though the Peter IV of Aragon assumed that Atumano would receive a higher dignity from the Roman Pope.
[9] Atumano was praised by his contemporary, Frederick III of Sicily, for his "innate goodness and praiseworthy character" and by his twentieth-century biographer as "no common scholar."
However, some latter day historians, especially the Catalan Antonio Rubió y Lluch, have labelled him an untrustworthy scoundrel on the basis of four documents in the archives of the Crown of Aragon in Barcelona dated to 1381 and 1382.
In one of the letters, Peter IV of Aragon requests that Urban VI remove Atumano from Thebes and replace him with John Boyl, the Bishop of Megara, exiled from his see since the Florentine occupation of 1374.