William II of Athens

William II (1312–1338), Duke of Athens, was the third son of Frederick III of Sicily and Eleanor of Anjou. When his brother Manfred died in 1317, William inherited the Catalan-ruled duchy while still a child.

His illegitimate half-brother Alfonso Fadrique governed the Greek lands for him and in 1319 added the Duchy of Neopatria; when Alfonso returned in 1330, William gave him Malta and Gozo. In 1335 he married María Álvarez de Jérica without papal dispensation, since the popes sought to check his father's power.

In 1337 Frederick left him Taranto, to pass to him after Eleanor's death, but William died first, in 1338. He was buried in Palermo cathedral and left his library to the city's Dominicans.