Merlyn
Merlyn was a powerful omniversal being associated with Captain Britain. He had many 'selves' among the realities of the omniverse, including Merlin the Wise. (COMIC: A Rag, a Bone, a Hank of Hair..., The Guns of Avalon)
At one point he and his daughter Roma resurrected Captain Britain after he had been killed by the Fury. (COMIC: A Rag, a Bone, a Hank of Hair...) Following this he murdered his own daughter and was imprisoned by his fellow Higher Evolutionaries. (COMIC: The Guns of Avalon)
History
Manipulating Captain Britain
At one point an incarnation of Merlin resurrected Captain Britain and later showed his daughter Roma several of his other incarnations. (COMIC: A Rag, a Bone, a Hank of Hair...)
Imprisonment by the High Evolutionaries
At some point the High Evolutionaries turned on Merlin, after he murdered his own daughter, and imprisoned him. Pete Wisdom was telepathically guided by Merlin to release him.
Behind the scenes
A link was established between the Marvel Comics' Merlyn, who has appeared in comics since 1943, and Doctor Who Magazine's Merlin the Wise when the character design of Merlin the Wise which first appeared in The Neutron Knights was shown as an alternate incarnation of Marvel's Merlin in A Rag, a Bone, a Hank of Hair.... This link was further solidified when Marvel's incarnation of Merlin later appeared in the altered reprint of Star Death released in The Daredevils #5, and the Neutron Knights' Merlin later appeared in a larger role throughout Paul Cornell's The Guns of Avalon in Captain Britain and MI-13 Vol 1 #3.