A red dwarf is a small, cool, very faint, main sequence star with a surface temperature under about 4,000 K. Red dwarves are the most common type of star. Proxima Centauri and 40 Eridani C (in the Vulcan system) are examples of red dwarf stars. The homeworld of Makull's species, an M-class planet, also orbited a red dwarf. (VOY: "Time and Again").

In astronomy, a red dwarf star is a small and relatively cool star, of the main sequence, either late K or M spectral type. They constitute the vast majority of stars and have a mass of less than one-half that of the Sun (down to about 0.075 solar masses, which are brown dwarfs) and a surface temperature of less than 3,500 K.

Their low surface temperature imparts to them a ruddy hue, while their combination of low temperature and small surface area results in them being very faint. Many red dwarfs are also flare stars.

Red dwarfs survive longer and are more numerous than any other kind of star, with the probable exception of brown dwarfs. Of the 30 nearest stars to the Sun, for example, 21 fall into this category. They include Barnard's Star, DX Cancri, Groombridge 34, Lacaille 9352, Lalande 21185, Luyten 726-8, Luyten 789-6, Proxima Centauri, Ross 128, Ross 154, Ross 248, Struve 2398 and Wolf 359.