Merlin is also known as Young Warlock, The Last Dragonlord, Magic, Dragoon The Great (Disguise), The Most Powerful Sorcerer To Ever Live, The Greatest Warlock Ever, The Greatest Sorcerer To Ever Walk The Earth, Great Emrys, Master (by Finna), Bog Man (by Gwaine)
The most known would be Emrys as other magical beings know him as.
He is a young warlock, the last Dragonlord in existence, the only son of Hunith and Balinor, Gaius's ward and apprentice, and the best friend and manservant of the late King Arthur Pendragon. Merlin is also a creature of the Old Religion. Having left his childhood in Ealdor for Camelot, Merlin became the manservant of the Prince of Camelot, Arthur Pendragon. From then on, acting on the prophecy of the Great Dragon, Kilgharrah, Merlin began his duty to protect and guide Arthur on his way to the throne, while he also had to secretly develop his magical gifts under the gaze of kings Uther and Arthur, both of whom despise the art. Merlin is suspected of sorcery many times during the series, the crimes he is accused of are invariably the work of others, and only Gaius and Lancelot are aware of his magic.
Merlin is destined to become the greatest and most powerful sorcerer to ever live, and to use his powers to free the magical people and revive the Old Religion to coexist with the New Religion. He is also destined to stand at Arthur's side as an advisor and partner, as he reunites all the kingdoms of the land back into Albion, calling forth an era of peace and prosperity.