- You may also be looking for a red supergiant.
A red giant is a very large, relatively cool star, formed when a main sequence star runs out of hydrogen and begins fusing helium. Some red giants were considered B class stars. (TNG: "We'll Always Have Paris")
The Vandor system was a binary star system that was comprised of a red giant and a pulsar. It was chosen by Paul Manheim as the site of his temporal experiments because of the system's unique gravity signature. (TNG: "We'll Always Have Paris")
The Kaelon sun, previously a yellow dwarf, was in the process of transforming into a red giant by 2367. It was expected to destroy its inhabited planet Kaelon II around the 2390s. (TNG: "Half a Life")
In 2377, a red giant was one of the obstacles during the Antarian Trans-stellar Rally. Tom Paris and B'Elanna Torres had to adjust the Delta Flyer's course when approaching it and recalibrated their sensors to compensate for photonic interference. (VOY: "Drive")
In 2383, Dal R'El unintentionally guided the USS Protostar to a binary system consisting of a red giant in the final stages of being torn apart by its white dwarf companion. The ship became caught in the white dwarf's gravity well, but managed to escape by riding the shockwave of the star's explosion. (PRO: "Starstruck")