<span class="SFPTagline"> From SCIFIPEDIA </span>

On the series Stargate SG-1, Merlin is an Ancient and the originator of the Arthurian myth of the great wizard. Once known as Moros, he was a member of the Atlantean council in the Pegasus Galaxy city of Atlantis. Moros first came into contact with humans from Earth when, following a disastrous visit to Atlantis, Dr. Elizabeth Weir traveled back in time hoping to gain their help in preventing the deaths of her expedition team. Moros was vocally against fulfilling her request to return to her own time using technology devised by the Ancient, Janus. ("Before I Sleep")

Shortly after those events, Moros was among the Ancients who evacuated to Earth. Over the next few thousand years, he lived among humans on Earth, helping in the spread of knowledge. He settled in England where he became known as Merlin and was responsible for the building of a treasure trove beneath Glastonbury Tor, protected by riddles and tests of strength and character. ("Avalon")

Merlin became a guiding force in the life of King Arthur and his knights. They would later travel to Camelot in search of the Sangraal created by Merlin and said to be hidden by Morgan le Fay. The sangraal was a device researched and created by Merlin to destroy ascended beings. At some point after having ascended like his fellow ancients, Merlin became convinced that the ascended beings known as The Ori were a threat that would need to be dealt with. Defying his fellow ascended, he returned to human form to create the Sangraal, hiding his research in another dimension. The ascended being, Morgan was sent to watch him and on his success ultimately destroyed the device. ("Arthur's Mantle")

Morgan eventually came to agree with Merlin and to protect his work, she created a series of trials meant to test those who would seek the device for their wisdom and purity of purpose. SG-1 passed her test and they were transported to a chamber where Morgan hid Merlin away in stasis. Merlin awoke and learning of the threat of the Ori, attempted to recreate the device. His body proved too weak to sustain the strain of the technology required and he downloaded his knowledge into a repository before his death. Daniel Jackson downloaded Merlin's knowledge and his memories into his own mind and continued his work. Though the Orici, Adria, stopped him before e could complete the device, he later managed to fulfill the goal using Merlin's knowledge ("The Quest, Part 2").