Nicol Williamson did not receive an Oscar nomination for portraying Merlin in Excalibur.
Excalibur tells the Arthurian legend.
The saving grace of the first half of the film, Nicol Williamson does what the film cannot, which is attempting to find some kind of balanced tone to make the material palatable. Williamson is a natural fit for the role of Merlin as he is an actor that exudes gravitas from every pour of his being. His voice, one of the greatest, yet sadly largely forgotten, in cinema commands attention with such ease. Although speaking of the voices one of the persistent flaws of the film is the poor sound design, which supposedly Boorman turned from stereo to mono, which perhaps is the cause of it, but it causes almost many to sound poorly dubbed, Nicol Williamson being the most major exception. Maybe Williamson just delivered his lines again with a greater thought to them, or maybe they were able to retain his audio, either way, it only adds to Williamson being the center of attention. Williamson himself adds to this through his performance that very carefully maneuvers the film's fantastical yet dark tone. Williamson in just the bluntest aspect does deliver on the very idea of the legend by being that powerful presence he is, that instantly commands the respect of Merlin as this figure of such a tremendous force. When his Merlin speaks with authority, that authority can only be seen as the truth due to Williamson's striking manner as a performer, and when he speaks you very much must listen, just as all men must listen to Merlin the sorcerer.
Merlin the sorcerer of Arthurian legend of course isn't this simple mentor wizard archetype, he's of a more complicated sort, even taking very questionable actions in his strange quest to see the legend of Arthur pass. Williamson's performance in turn isn't so simple as just there to deliver the gravitas to these early moments, something he does, but rather he helps out the film greatly by taking a bit out of the film's aggressively dramatic tone. Williamson pulls off a fascinating trick which is that he both takes the material very seriously, yet also doesn't take it seriously at all. There is a cheekiness that Williamson brings to his performance that is a welcome relief through the film's overall insanity of the legend, which seems particularly important given the initial mechanizations of the film involve Merlin basically getting a King laid that will lead to the birth to the eventual King Arthur (Nigel Terry). Williamson realizes a remarkable method of being able to speak the words to create the spell to create this scenario with the utmost seriousness, however, at the same time, his eyes can denote this certain calculation about Merlin, a knowing quality within the character. Williamson's method makes it so it does grant the idea of Merlin's foresight into the knowledge of the future that he is in a way purposefully composing a destiny, while also just making Merlin seem beside it all in his own way as the entity who walks on a different mental plane.
Essentially as the film runs its course in the first half, which I do think is a lot of noise for the most part, Williamson consistently is the one who clears it away with his portrayal of Merlin's very specific machinations, which includes as much as taking a mother's child in order to fulfill destiny. Williamson though carries himself with such a powerful stride that manages to craft a properly entertaining spirit out of the cunning sorcerer. His manner as the advisor to Arthur, and in a strange way Arthur's nefarious sister Morgana Le Fay (Helen Mirren), who is also a magic user, is that of many things. There is a bit of warmth he does bring to his interactions with Arthur, but there is also that sense of intelligence as Williamson delivers every thoughtful suggestion with the sense of a man who has seen the future. Williamson though naturally delivers comedy in that same idea like when it seems like Arthur is lusting like the old King, and Williamson's sudden and annoyed reaction is pitch-perfect hilarity as the sorcerer who has had enough of the lusts of man. Although speaking of lusts, Williamson's scenes with Mirren are so carefully realized as Williamson presents still this certain captivating command as he instructs her almost in this dismissive way, while also conveying this certain internalized intrigue in her just as Merlin claims he cannot be captured by lust. Williamson is always compelling while making these qualities of Merlin seem consistent within the singular being of Merlin.
Although as destined at a certain point Merlin finds himself imprisoned, which was very concerning, thankfully the rest of the film comes together to a pretty triumphant film in the second half even without Williamson around to steer the ship. If the film had left Merlin at that moment that might've been enough to be a great performance, nonetheless the greatest scenes of Williamson's come in the final act as Merlin returns to help Arthur one last time. Williamson is genuinely amazing in the scene as Arthur hopes for Merlin to help because it illustrates the magnificent juxtaposition he so effortlessly pulls off. As we have Williamson open the moment with such potent sincerity and affectionate warmth as Merlin notes that Arthur's love brought him back as a dream. I love the look of pride on Williamson's face as he looks upon Arthur at this point as a proud father. But it is only Williamson perhaps who could go from such a tender delivery of "a dream to some" and then such ferocious intensity as he finishes "a nightmare to others". Williamson showing in just one magnificent line delivery, which contains such a dramatic yet effective shift from calm earnestness to tremendous grandeur, powerfully realizes the nature of this Merlin. His final scene of dispatching Morgan by getting her to speak a self-destructive spell is outstanding. Williamson chooses such a fascinating choice as he speaks in whispers, yet whispers that only Williamson could do as never have whispers captured more intensity. Williamson in this manages to speak in this almost seductive come hither to Morgana, convincingly so, while at the same time his eyes speaking the truth of his real intent towards such hatred for the evil witch. Williamson is absolutely wonderful in crafting this killing blow as Merlin pesters her with compliments, destroying her with this mischievous praise. An altogether brilliant scene due to Williamson's masterful choices as a performer. Williamson though masters the material entirely within his great performance that always manages to maneuver in just the right way to realize a perfect hypocrisy by playing material wholly as truth, while also not exactly taking it all that seriously.
