Sextus is an ancient Roman praenomen or "first name". Its standard abbreviation is Sex., and the feminine form would be Sexta. It is one of the numeral praenomina, like Quintus ("fifth") and Decimus ("tenth"), and means "sixth". Although it is sometimes thought that these names originally referred to birth order and were then handed down through the family line, they may have also been a reference to the month of birth. Similar names were used among the Sabellians. The gens name Sextius is a related form.

Among those named Sextus are: