Hades, the god of the underworld, was not actually banished from Olympus. In Greek mythology, Hades is one of the three major gods who divided the world among themselves. Zeus became the ruler of the sky, Poseidon took control of the seas, and Hades was given dominion over the underworld.
Hades’ role as the ruler of the underworld meant that he spent most of his time there, overseeing the dead and maintaining order in his realm. This is often misunderstood as a banishment, but it was actually a division of responsibilities among the three brothers. Hades was not excluded from Olympus; he simply had his own domain to manage.
In some myths, Hades does visit Olympus, especially during important gatherings of the gods. However, his primary duty was to the underworld, which is why he is often associated with that realm rather than Olympus.