Numa Pompilius in the context of "Februarius"

The Roman deities most widely known today are those the Romans identified with Greek counterparts, integrating Greek myths, iconography, and sometimes religious practices into Roman culture, including Latin literature, Roman art, and religious life as it was experienced throughout the Roman Empire. Many of the Romans' own gods remain obscure, known only by name and sometimes function, through inscriptions and texts that are often fragmentary. This is particularly true of those gods belonging to the archaic religion of the Romans dating back to the era of kings, the so-called "religion of Numa", which was perpetuated or revived over the centuries. Some archaic deities have Italic or Etruscan counterparts, as identified both by ancient sources and by modern scholars. Throughout the Empire, the deities of peoples in the provinces were given new theological interpretations in light of functions or attributes they shared with Roman deities.

A survey of theological groups as constructed by the Romans themselves is followed by an extensive alphabetical list concluding with examples of common epithets shared by multiple divinities.

In ancient Roman religion and mythology, Jupiter (Latin: Iūpiter or Iuppiter, from Proto-Italic *djous "day, sky" + *patēr "father", thus "sky father" Greek: Δίας or Ζεύς), also known as Jove (nom. and gen. Iovis [ˈjɔwɪs]), is the god of the sky and thunder, and king of the gods. Jupiter was the chief deity of Roman state religion throughout the Republican and Imperial eras, until Christianity became the dominant religion of the Empire. In Roman mythology, he negotiates with Numa Pompilius, the second king of Rome, to establish principles of Roman religion such as offering, or sacrifice.

Jupiter is thought to have originated as a sky god. His identifying implement is the thunderbolt and his primary sacred animal is the eagle, which held precedence over other birds in the taking of auspices and became one of the most common symbols of the Roman army (see Aquila). The two emblems were often combined to represent the god in the form of an eagle holding in its claws a thunderbolt, frequently seen on Greek and Roman coins. As the sky god, he was a divine witness to oaths, the sacred trust on which justice and good government depend. Many of his functions were focused on the Capitoline Hill, where the citadel was located. In the Capitoline Triad, he was the central guardian of the state with Juno and Minerva. His sacred tree was the oak.

In ancient Roman religion and mythology, Mars (Latin: Mārs, pronounced [maːrs]) is the god of war and also an agricultural guardian, a combination characteristic of early Rome. He is the son of Jupiter and Juno, and was pre-eminent among the Roman army's military gods. Most of his festivals were held in March, the month named for him (Latin Martius), and in October, the months which traditionally began and ended the season for both military campaigning and farming.

Under the influence of Greek culture, Mars was identified with the Greek god Ares, whose myths were reinterpreted in Roman literature and art under the name of Mars. The character and dignity of Mars differs in fundamental ways from that of his Greek counterpart, who is often treated with contempt and revulsion in Greek literature. Mars's altar in the Campus Martius, the area of Rome that took its name from him, was supposed to have been dedicated by Numa, the peace-loving semi-legendary second king of Rome; in Republican times it was a focus of electoral activities. Augustus shifted the focus of Mars's cult to within the pomerium (Rome's ritual boundary), and built a temple to Mars Ultor as a key religious feature of his new forum.

Fontus or Fons (pl.: Fontes, "Font" or "Source") was a god of wells and springs in ancient Roman religion. A religious festival called the Fontinalia was held on October 13 in his honor. Throughout the city, fountains and wellheads were adorned with garlands.

Fontus was the son of Juturna and Janus. Numa Pompilius, second king of Rome, was supposed to have been buried near the altar of Fontus (ara Fontis) on the Janiculum. William Warde Fowler observed that between 259 and 241 BC, cults were founded for Juturna, Fons, and the Tempestates, all having to do with sources of water. As a god of pure water, Fons can be placed in opposition to Liber as a god of wine identified with Bacchus.