Count: 0 — No established French last names beginning with the letter X appear in the major French surname sources (INSEE frequency lists, national civil registries, standard etymological dictionaries, and leading genealogical databases). Note the interesting detail that the letter X is common inside French words and shows up in regional or foreign family names that enter French usage, but it is strikingly rare as the first letter of native French surnames.

Understand that this absence reflects phonetics, orthography, and history. French rarely begins words with X, and many names that do start with X come from Basque, Catalan, Spanish, or Portuguese origins rather than from core French naming traditions. Historical spelling shifts and standardization have also reduced medieval X-initial forms. Official frequency lists and civil records therefore register few or no widely used French family names that meet strict criteria for a national, authoritative A–Z surname list.

Include close examples instead of forcing unverified entries. Xavier exists widely as a given name and appears as a surname in some records, and historical Gascon names such as Xaintrailles occur in older documents, while Basque surnames beginning with X appear regionally in francophone areas. Treat these as borderline or regional entries: list them with clear origin notes, show variant spellings and accents, and prioritize only those names that authoritative sources actually record for modern French usage.