Answer: Cerberus
Some extra relevant information:
In Greek mythology, the name of Hades’ fearsome three-headed dog that guarded the gates of the Underworld was Cerberus. This monstrous creature was known for its ferocity and imposing presence. Cerberus was tasked with preventing the living from entering the realm of the dead and ensuring that the souls of the deceased couldn’t escape. The name Cerberus is believed to have originated from the Greek word “kerberos,” which means “spotted.” The three heads of Cerberus were said to symbolize his ability to see the past, present, and future simultaneously. This legendary creature played a significant role in Greek mythology, appearing in various stories and serving as an iconic symbol of the Underworld’s impenetrability.