E. Rossoni proposes that the surnames of this family would derive, directly or through diminutives, from the Latin cognomen Herculius or from the medieval name Hercules. For his part, A. Bongioanni develops the etymology in greater detail: the name goes back to a Latin divinity whose original function was the defence of the boundaries of property, derived from the verb hercere, with the sense of "to close and delimit"; later it was identified with the Greek Heracles. Bongioanni also notes that in the ancient writers the name appeared in the form of the nominative with an accent on the last vowel: Ercolés, in the manner of Achillés or Diogenés.

V. Blunda, on the other hand, proposes a different etymological route: he derives the surname directly from the Greek Eraclès, that is, from the personal name Heracles preserved in the onomastic tradition of the Mediterranean, and links it to eastern Sicily. He also notes its parallelism with the surname Eraclèo, derived from the same ancient Greek etymon.

As for the variants and their geographical distribution, Rossoni indicates that Ercole presents specific zones in the Naples area, in Rome and in the L'Aquila area, with presence also in the Genoa area and in Piedmont; Ercoli appears in at least four zones of central Italy: in Lazio, in Umbria, in the Marche and in Tuscany; Ercolini seems to be typical of the area comprising the provinces of Massa, Lucca and Pistoia, with presence also in Milan and Rome; and Ercolino is characteristic of the Foggia and Avellino areas, with an additional presence in Rome.

Bongioanni provides complementary data on specific variants: the surname Erculés is peculiar to Turin, while Ercolessi is Tuscan. He also records the surnames Ercolani and Hercolani, derived from Ercolano —bishop of Perugia and martyr under Totila, whose feast is celebrated on 7 November—. He also notes that the name Ercole was frequent among the Este and Farnese houses. Finally, he mentions that from a feminine name Madonna Arcolonia —that is, Ercolania— the Udine family known as Arcoloniani, today extinct, took its surname. Bongioanni adds also that the Greek Church venerates twelve saints with the name of Heracles.