second of the seven kings who, according to Roman tradition, ruled Rome before the founding of the Republic (c. 509 BC).

Numa is said to have reigned from 715 to 673. He is credited with the formulation of the religious calendar and with the founding of Rome's other early religious institutions, including the Vestal Virgins; the cults of Mars, Jupiter, and Romulus deified (Quirinus); and the office of pontifex maximus. These developments were actually, however, the result of centuries of religious accretion. According to legend, Numa is the peaceful counterpart of the more bellicose Romulus (the legendary founder of Rome), whom he succeeded after an interregnum of one year. His supposed relationship with Pythagoras was known even in the Roman Republic to be chronologically impossible, and the 14 books relating to philosophy and religious (pontifical) law that were uncovered in 181 BC and attributed to him were clearly forgeries.