What are large stars in late life stages called?

Large stars in their late life stages undergo significant changes as they exhaust their nuclear fuel. As a result, they expand and cool, transforming into what are known as red giants. This phase occurs after the star has burned through its hydrogen and begins to fuse helium and other heavier elements. The outer layers of the star expand dramatically, and the star's color shifts to red due to the decrease in surface temperature.

Red giants represent an important phase in stellar evolution, particularly for stars that started off with a much larger mass than our Sun. The eventual fate of these red giants can lead to various outcomes, including further transformation into more exotic objects such as supernovae or, in some cases, the formation of planetary nebulae followed by white dwarfs for less massive stars. However, the defining characteristic of a large star in this particular late stage is indeed its transition to being classified as a red giant.