Supergiant
Supergiants are the old forms of old main sequence stars that had a high mass. These expanded when hydrogen ran out for fusion in their core to become red and blue supergiants. Typically, when the hydrogen in the core runs out, the star becomes a red supergiant when hydrogen fusion occirs in a layer surrounding the core. When helium fusion starts, the red supergiant becomes a blue supergiant. When the core becomes multi-layered with heavier elements being produced by fusion, it becomes a red supergiant again. However, supergiants may go through the red-blue supergiant cycle numerous times, and both red and blue supergiants can end their life in a supernova explosion.