The origins and identities of two Fabrician butterfly species now included in the genus Arhopala Boisduval, 1832, are examined; the species are Papilio centaurus Fabricius, 1775, and Hesperia democritus Fabricius, 1793 (Lepidoptera: Lycaenidae). To dispel recent confusion, complete taxonomic histories are presented for both. The type locality of Arhopala centaurus is established as near Jakarta, Java, and that of Arhopala democritus as Phuket Island, south-western peninsular Thailand. Amblypodia pseudocentaurus Doubleday, 1847, described from Java, is re-established as a subjective synonym of Arhopala centaurus sensu stricto. The subspecies of centaurus that flies in the Malay Peninsula is re-established as A. centaurus nakula (Felder & Felder, 1860). The distinct Australian species misidentified in recent literature as Arhopala centaurus should be known as Arhopala eupolis (Miskin, 1890). Lectotype designations are made for the nominal species Papilio centaurus, Hesperia democritus, Amblypodia pseudocentaurus and Amblypodia nakula.