What surprising dual membership exists within the M-class spectral category?

Answer

It includes the extremely numerous, low-mass red dwarfs and the largest stars, the red supergiants.

While M-class stars are mostly small, common red dwarfs, the class also encompasses red supergiants, which are gargantuan stars representing a late evolutionary stage.

What surprising dual membership exists within the M-class spectral category?
astronomytemperaturestarsstellar evolutioncommonality