Eustacio is a compelling given name of Latin origin, derived from the Roman family name Eusto, which was also used as an adjective meaning 'upright' or 'upright in character'. The name gained popularity during the Middle Ages through its association with Saint Eustace, a Christian martyr who was venerated for his faith and courage. Throughout history, Eustacio has been employed by various cultures, particularly among Hispanic communities, where it is often used as an alternative to the more common Eustace.
The name Eustacio appears to have had some popularity during the mid-20th century, with the highest number of births occurring in 1951 and 1952, each having 7 births. However, it seems that the name has not been particularly popular overall, as there are only 292 recorded births over nearly a century, from 1915 to 2006. The name appears to have had periods of relative popularity in the 1940s and again in the late 1980s and early 1990s, but it has never been among the most popular names in any given year during this time period.