Alexander the great was so named because he

Alexander's achievements earned him the moniker 'the Great.' Not only did he take the throne at a young age, but he accomplished much within the short span of his rule. Alexander's conquest of other countries acquired him one of the biggest empires known in ancient times. His military prowess and incredible leadership, as well as his noted kindness to the people he conquered, earned him his nickname 'Alexander the Great,' which was given to him after his death.