Two great favourites of mine are Merlin the wizard (whose legends are all around Britain, including the nearby England-Scotland borders) and St Cuthbert the Wonderworker (who also lived fairly near to me on the island of Lindisfarne, and is still quite well remembered locally - at least in the names of places and institutions)-
Merlin and Cuthbert present interesting similarities and contrasts.
There is, of course, no remotely definitive story of King Arthur - since it is the dominant piece of genuine 'folk-lore' of England (even though British rather than English - having pretty much displaced the specifically English folk hero of Robin Hood). Like everybody, I have encountered innumerable versions of the Arthurian legends.
But the general character of Merlin is pretty consistent: a powerful wizard: kindly, broadly well-meaning, but irritable and prone to sarcasm - and morally ambiguous.
Merlin is essential to the creation and survival of the Good kingdom and the Good King; yet he is a worldly figure: he does dubious enchantments for dubious reasons (e.g. the shape-shifting spell to satisfy the King Uther's rapacious lust, leading to the birth of Arthur).
And, in many versions, Merlin comes to a sticky end - often by falling in love with a beautiful but wicked enchantress (e.g. Nimue or Vivienne) and teaching her his secrets - as a result Merlin may be imprisoned forever (or for centuries) in a tree, or crystal cave.
In other versions Merlin became a military leader, but was defeated, escaped into the wilderness to die as a raving lunatic bewailing his loss of power and prestige.
While Merlin's damnation is not definite, and repentance and salvation is not necessarily ruled-out - at best the possibility is suspended.
St Cuthbert, by contrast, is perhaps the holiest Saint of England.
And, by contrast with the garbled legends of Merlin, Cuthbert's principal biographer was the first and one of the greatest English historians: The Venerable Bede of Jarrow and Monkwearmouth.
Cuthbert was a monk (later and briefly a Bishop): an extreme ascetic, who prepared for his miracle-working years by many years of disciplined prayer, learning by heart of scriptures, fasting, vigils (staying up all night praying), participation in Church rituals and other hardships.
St Cuthbert, in contrast with Merlin, was one of those Saints who were regarded as having lived both in Heaven and on Earth in his later years, he had a glorious and inspiring death and went (it is presumed) to the high place prepared for him.
Cuthbert was immediately widely venerated, many Churches were founded in his name, and his memory and scattered relics were the subject of marvellous stories and the attributed cause of numerous miracles.
A long distance footpath called St Cuthbert's Way was recently created to trace the important places of his life and the route of his posthumous remains:
Yet, for moderns, the powerful but flawed and ultimately tragic figure of Merlin seems much more exciting than Cuthbert.
The hints (and more than hints) of intoxicating and depraved lust which were Merlin's downfall, and which he seemed to embrace either helplessly or willingly, are just the kind of thing to strike a chord in our era.
The comparison illustrates a change of ethos, and a scaling-down of ambition. St Cuthbert's example is so far above anything attainable to us moderns that it is almost intimidating rather than inspiring to weak and corrupt individuals such as myself!
The comparison also illustrates the Eastern Orthodox understanding of miracles, magic and wonders.
The Orthodox belief is that miracles and magic are real and accessible, but hazardous - because they can be achieved with either divine/ angelic or demonic assistance (and because demons are deceptive and can masquerade as angels).
Merlin was certainly attributed with advanced magical powers and in some version was actually demonic in origin - e.g. with a demon father magically inseminating a virgin mother, with the intention of producing an Antichrist; but then having been blessed and baptized in the womb by a Saint, to emerging as the morally ambiguous - but broadly benign - trickster figure we know.
At any rate, it would be expected that some, at least, of Merlin's powers were demonic rather than divine; and that the demons exacted the usual payments.
A traditional Orthodox view would probably be that Merlin came to grief in using magic because he was (ultimately) proud and lustful rather than humble and loving; because he sought and served power rather than disinterested knowledge; and insofar as he did not repent his pride and lust.
(Repentance not being the same as regret, or shame, or wishing things had turned-out otherwise.)
While St Cuthbert had - by long ascetic preparation - attained the necessary humility and love to be able (after this was attained, not before) to be permitted to deploy divine and angelic powers in the service of Good.
This seems to be the essential difference between a Saintly Wonderworker and a wizard like Merlin - and the (non-Saintly) White wizard's goodness is seen as inevitably tenuous, and mixed; and the temptation to darkness un-ceasing and eventually irresistible.