Appius (Ap.) — only used by gens Claudia.
Aulus (A.) or Olus.
Caelus — from Etruscan Caele.
Decius — associated with the gens Minatia.
Decimus (D.) — “tenth”.
Faustus — “lucky” an archaic praenomen revived by the dictator Sulla for his twin children. Used by his descendants ever after. Uncommon.
Flavius — from flavus (“golden”), imperial praenomen after the 3rd century. The name survived into the eighth century AD.
Gaius (C.) — often written as “Caius”, because it was originally spelled that way before C and G were separated. From Etruscan Cae or Cai, meaning unknown.
Gnaeus (Cn.) — often written as “Cnaeus”.
Kaeso (K.) or Caeso — “Cut from the womb”. Uncommon. Only used by gens Fabia.
Lucius (L.) — common.
Mamercus (Mam.) — from Etruscan Mamerce. Associated with gens Aemilia Lepida.
Manius (M'.) — “Morning”. Uncommon, “M'.” often confused with “M.”
Marcus (M.) — from Etruscan Marce, meaning unknown. There may be a connection with Mars if he turns out to be of Etruscan origin. Common.
Mettius — from Etruscan Metie.
Numerius (N.) — from Etruscan Numesie, associated with gens Fabia.
Octavianus (O.) — “eight”.
Publius (P.) — from publius (“public”), common, originally Etruscan Puplie. Latin populace is probably from the same Etruscan word, as Pupluna became Populonia in Latin.
Quintus (Q. or Qu.) — “fifth”. Common.
Secundus — “second”.
Septimus (Sept.) — “seventh”.
Servius (S. or Ser.) — from servo (“to preserve”); uncommon.
Sextus (Sex.) — “sixth”.
Spurius (Sp.) — from spurius (“of illegitimate birth”).
Tertius — “third”.
Tiberius (Ti.) — from Etruscan Thefarie, probably from the river; common.
Titus (T.) — from Etruscan Tite, meaning unknown. The spurious Indo-European derivation, titulus (“title of honor”), is a superseded theory. Common.
Amulius
Agrippa — “Born feet first”.
Arruns — Of Etruscan origin.
Camillus — Only used by gens Furia and gens Arruntia combined. Better known as a cognomen.
Canus
Cossus
Drusus — Only used by gens Claudia.
Gallus
Herius — Only used by gens Asinia.
Hostus
Lar(s) — Of Etruscan origin.
Marcellus. More commonly known as a cognomen
Nonus — “Ninth”.
Opiter — Associated with gens Verginia.
Oppius
Paul(l)us
Postumius — “Born after (his father's) death”.
Potitus
Primus — “First”.
Proc(u)lus
Sisenna
Tullus
Vel — Of Etruscan origin.
Vibius
Vopiscus — At early times associated with gens Claudia.