The Temple of Portunus is an ancient Roman temple located in Rome, Italy. It was built beside the Forum Boarium, the Roman cattle market associated with Hercules, which was adjacent to Rome's oldest river port and the oldest stone bridge across the Tiber River, the Pons Aemilius. It was probably dedicated to the gateway god Portunus although the precise dedication remains unclear as there were several other temples in the area besides his. It was misidentified as the Temple of Fortuna Virilis from the Renaissance and remains better known by this name. The temple is one of the best preserved of all Roman temples.

Ancient Roman temples were among the most important buildings in Roman culture, and some of the richest buildings in Roman architecture, though only a few survive in any sort of complete state. Today they remain "the most obvious symbol of Roman architecture". Their construction and maintenance was a major part of ancient Roman religion, and all towns of any importance had at least one main temple, as well as smaller shrines. The main room (cella) housed the cult image of the deity to whom the temple was dedicated, and often a table for supplementary offerings or libations and a small altar for incense. Behind the cella was a room, or rooms, used by temple attendants for storage of equipment and offerings. The ordinary worshiper rarely entered the cella, and most public ceremonies were performed outside of the cella where the sacrificial altar was located, on the portico, with a crowd gathered in the temple precinct.