What is the most common type of star?
Red dwarf
Red dwarfs are by far the most common type of star in the Milky Way, at least in the neighborhood of the Sun, but because of their low luminosity, individual red dwarfs cannot be easily observed. From Earth, not one is visible to the naked eye. Proxima Centauri, the nearest star to the Sun, is a red dwarf (Type M5, apparent magnitude 11.05), as are fifty of the sixty nearest stars.
According to some estimates, red dwarfs make up three-quarters of the stars in the Milky Way.
Red supergiant star
The "red" part of "red supergiant" refers to the cool temperature. Red supergiants are the coolest supergiants, M-type and at least some K-type stars although there is no precise cutoff. K-type supergiants are uncommon compared to M-type, because they are a short-lived transition stage and somewhat unstable. The K-type stars, especially early or hotter K types, are sometimes described as orange supergiants (e.g. Zeta Cephei), or even as yellow (e.g. yellow hypergiant HR 5171A).