Is Barthélemy also a surname?

Yes. Barthélemy is used as a surname as well as a first name; its surname page has the origin and how many people carry it.

The first name Barthélemy

A unisex name.

4 syllables Unisex Also a surname

19 on Wikidata, most written-about first

Barthélemy Boganda
1st Prime Minister of the Central African Republic autonomous territory (1910-1959)
Barthélémy Du Mortier
Belgian politician and botanist (1797-1878)
Barthélémy Catherine Joubert
French general (1769–1799)
Barthélémy de Theux de Meylandt
Belgian politician (1794-1874)
Barthélemy d'Eyck
Early Netherlandish painter and manuscript illuminator (1420-1470)
Barthélémy Chinenyeze
French volleyball player, born 1998
Barthélemy d'Herbelot
French orientalist (1625–1695)
Barthélemy Faujas de Saint-Fond
French geologist, 1741–1819
Ernest Amédée Barthélemy Mouchez
French astronomer, admiral and scientific collector (1821 – 1892)
Barthélemy Louis Joseph Schérer
French general (1747-1804)
Barthélemy Thimonnier
French inventor who invented the first sewing machine (1793–1857)
Barthélémy Toguo
Cameroonian painter (born 1967)

Is Barthélemy also a surname?: Yes. Barthélemy is used as a surname as well as a first name; its surname page has the origin and how many people carry it.