An epigraphical survey (with digital mapping component) of Greece and Magna Graecia reveals a pattern as to where Hephais-based names appear, up through the second century BCE. Spelled with an /eta/, these names are almost exclusively Attic-Ionian, while Haphēs-based names, spelled with an alpha, are Doric-Aeolian, and much fewer in number. There is virtually no overlap, except at the Panhellenic site of Delphi, and in a few colonies around the Black Sea. Furthermore, cult for the god Hephaistos –long recognized as a non-Greek borrowing– was popular primarily in Attic-Ionian and “Pelasgian” regions, precisely the same areas where we find Hephais-root names. The only area where Haphēs-based names appear in any quantity, Boeotia, also had an important cult related to the god. Otherwise, Hephaistos was not a terribly important deity in Doric-Aeolian populations. This epigraphic (and religious) record calls into question the assumed Macedonian ethnicity of the king’s best friend and alter-ego, Hephaistion. According to Tataki, Macedonian naming patterns followed distinctively non-Attic patterns, and cult for the god Hephaistos is absent in Macedonia (outside Samothrace). A recently published 4th century curse tablet from Pydna could, however, provide a clue as to why a Macedonian Companion had such a uniquely Attic-Ionian name. If Hephaistion’s ancestry was not, in fact, ethnically Macedonian, this may offer us an interesting insight into fluidity of Macedonian identity under the monarchy, and thereby, to ancient conceptualizations of ethnicity more broadly.