The Theme of Sicily (Greek: θέμα Σικελίας - Thema Sikelias) is an East Roman (Byzantine) military-civilian province (thema, theme) existing from the late seventh to the tenth century, encompassing the island of Sicily and the region of Calabria in the Italian mainland.

Following the Muslim conquest of Sicily, from 902 the theme is limited to Calabria, but retains its original name until the middle of the tenth century.