0 — No verified Latin boy names that start with Z meet the stated criteria. You requested names grounded in classical Latin sources, Roman praenomina/nomina, saints’ lists, and scholarly references. Interesting detail: Classical Latin rarely uses Z as an initial letter, so native Latin personal names beginning with Z are effectively absent from the authoritative record.

Understand that this absence has clear historical and linguistic causes. The Latin alphabet and phonology give Z a marginal role: early Latin largely dropped Z and later reintroduced it only for Greek loanwords. Roman naming conventions (fixed praenomina and common nomina) did not produce Z-initial personal names, so no native Latin-origin boys’ names start with Z in the classical corpus.

Consider close matches if you relax the “native Latin” requirement. Names such as Zeno, Zosimus, Zenobius, and Zacharias appear in Latin texts as Latinized Greek or Hebrew names and are common in medieval and ecclesiastical contexts. If you want a usable list, broaden the scope to “Latinized names used in Latin” or to Latin names that contain Z elsewhere, or look at Greek- and Hebrew-origin saints’ names that were adopted into Latin usage.