Myrddin, who would become known as Merlin the Magician, was born one of the younger sons of the archfiend Belial. His older brother Etrigan was a powerful Demon, and his rise through the ranks of Hell would shape Myrddin's own future, as it did his other brother Lord Scapegoat who spent his life being blamed for Etrigan's doings. Belial arranged for his son to be trained in the arts of sorcery, so that Merlin might one day bind and control Etrigan, his half-brother. As a result he spent years on the earthly plane being taught the secrets of magic. He would eventually become one of the most powerful magicians of the age.
While he was eventually able to bind his brother, during his time on earth Merlin became involved with the affairs of Camelot, and served in the role history and Myth remembers him for as the adviser to King Arthur. When Camelot was threatened he did all in his power to protect it, even going so far as to unleash Etrigan to battle the forces of Morgain Le Fey, intent on usurping King Arthur's Court at Camelot. After Le Fey's defeat and Camelot's fall, Merlin bound Etrigan to the druid Jason, who became Jason Blood.
Merlin went on to continue to meddle in the affairs of man. He has a connection to all incarnations of the Shining Knight and also to the Silent Knight. One such project of his was Tim Hunter, Merlin was the boy's spiritual father setting him up with an impressive amount of magical power and an incredibly destiny. Merlin manipulated events from afar, until the boy was ready to truly begin his training, then helping him to learn his true names to gain entrance into the white school.
At an unknown time Myrddin (or the demonic portion) ascended. Over the years he scioned his own line on earth, a group of powerful descendants who gathered together as the Council of Merlin. When the books of Magic where r
e-written they seized the opportunity to attempt to garner the powers of SHAZAM for themselves. As the end of their gambit neared, they approached Merlin in his realm to seek his aid. Though he was at first weary of them, he in the end was convinced to lend them his power. He powered the spell that would have allowed Sabina to garner the powers of Shazam. Though in the end she failed him, Myrddin was un-disturbed, biding his time for another chance to strike.
Batman: The Brave and the Bold
In fifth episode "Day of the dark knight!" during a prison riot in Iron Heights, Batman and Green Arrow compete each other fighting with criminals attempting to escape, when most of the prisoners were defeated an old man appeared and invoked a spell that transported the heroes to England of the fifth century AD. The man introduced himself as Merlin Ambrosius.
The wizard transported the chosen heroes to the past in order to defeat Morgaine Le Fey, a former student of him and sister of King Arthur who revealed herself against Merlin and King Arthur to rule Camelot as Queen. The only hope to beat Le Fey was the ancient sword Excalibur, hidden in the Tower of the Excalibur, only one of the heroes would be worthy enough to take the sword from the stone.
During their journey they were attacked by Le Fey minions and Etrigan The Demon controlled by the sorceress. The heroes prevailed the first encounter and continued their journey. The witch angered by the defeat of her slave attacked mesmerizing Batman and giving him a medieval armor in order to take the sword on behalf of her. Merlin released Batman and Etrigan from their spell. Seeing herself betrayed the sorceress turned into a dragon. In battle the witch turned to stone Merlin and Etrigan. Batman and Green Arrow drew the sword from the stone and Green Arrow used Excalibur as an arrow to killed the beast. At the end of the episode Merlin returned heroes to their time.
Merlin was voiced by David McCallum.