The Nebulon-B Frigate is a starship from the fictional Star Wars universe. Built before and during the Galactic Civil War, this ship was used by both sides of the battle as a support ship for the large capital ships, such as Imperial Star Destroyers and Mon Calamari Cruisers. It was often used by the Rebellion during the war, with the most famous instance of this ship being the Medical Frigate seen in the movie Return of the Jedi. Built by a subsidiary of the massive galactic Kuat Drive Yards corporation, the ship mounts twelve turbolaser batteries and twelve laser cannons. A Nebulon-B Frigate carries 24 starfighters.

The Nebulon-B was never very successful in its design role as convoy escort. Enemy forces soon found countermeasures and a number of those frigates defected to the Rebel Alliance. For a time the Rebel Alliance used them as command ships for raids into the Empire but they were replaced by the far more capable Mon Calamari cruisers and modified for other uses or became dedicated fleet escorts.

However, it was a relatively cheap escort and was found in great numbers across the galaxy despite its relative inefficiency and the vulnerability of the neck.

Some time after the destruction of the Second Death Star, an improved version called the Corona was created specifically for the Galactic Empire. The B2 looked similar to two of the original type fixed together at a 45 degree angle, so that the bottom-facing "wings" made an upside-down "V" shape. It has sometimes been called the Nebulon-B2.