At the beginning of the manga, Meliodas is 3000 years old. After the events of the purgatory, his age would be estimated to be over 6000 years. Demons have a greater longevity and age extremely slowly. However, Meliodas is immortal due to a curse, meaning he does not age.
Meliodas has a brother named Zeldris. Zeldris is an elite warrior of the Demon Clan, serving directly under the Demon King as the leader and Piety of the Ten Commandments. He is the younger brother of Meliodas and the youngest son of the Demon King, whom Zeldris also serves as a representative and executioner.