Who was the Roman god of fire and the forge?

The Roman god of fire and the forge was Vulcan.

Vulcan governed fire, metalworking, volcanoes and the forge in ancient Roman religion. His hammer and anvil represent the productive power of heat: fire could destroy buildings and crops, but it could also transform raw metal into weapons, tools and finely made objects.

Romans identified Vulcan with the Greek smith-god Hephaestus. In Roman tradition, however, Vulcan also had an important role in protecting the city from destructive fire. His oldest sanctuary, the Vulcanal, stood near the Capitoline at the edge of the Roman Forum, where an open-air sacred fire was maintained.

His annual festival, the Vulcanalia, was held on August 23. Romans offered sacrifices to help avert dangerous fires, particularly around harvested grain. Vulcan is often confused with Mars because both can be connected with weapons, but Mars is the god of war; Vulcan is the divine maker who forges them. His name also survives in “volcano,” reflecting his association with subterranean fire.