Alain Delon did not receive an Oscar nomination for portraying Jef Costello in Le Samourai.
Alain Delon plays the titular character of Le Samourai who obviously is not an actual samurai, but technically speaking just a gun for hire. Jef Costello, which is incidentally a far less awesome title than his titular moniker, does not act as some sort of crude hired killer though. This is evidenced from his earliest scene where he lays in bed where he smokes waiting before he goes on his assignment. Delon's performance is almost a silent performance actually. Delon does speak in the film from time to time but it is mostly in one word responses or in the simplest of sentences that are only meant to serve the most basic instructional purposes. There really is very little in terms of dialogue between Costello and anyone, and there is even less in terms of Costello verbalizing whatever it might be that he is going through. Delon's work is mostly all based around what he does physically in the role, and is an interesting example of what an actor can do in a purposely limited part.
Well Delon is rather brilliant in the way he carries himself in the film. Even the way he just smokes in the bed Delon makes less an act of inhaling smoke to rather some sort of preparatory ritual that the samurai must do before he kills. After stopping smoking though the samurai prepares himself by getting dressed in his trench coat and putting on his hat. Although kudos to the costuming, but Delon certainly wears it his own way. There is something so remarkable even just about that way that Delon always puts on Costello's hat. There is just something so, for a lack of a better word, cool about the way Delon removes and wears that hat. It isn't just some guy wearing a hat, even though technically that's all that it is, Delon somehow makes it more than that. The way he does it has this certain emphasis of a warrior preparing himself for his task rather than of a thug with a gun which again that really is all that Jef Costello really is.
Delon even in the way he walks there is something special about it. The concise steps he takes at all times show a man absolutely driven for this precision of a master swordsman more than a master with the gun. Everything that Delon does adds to this characterization of Costello as slightly otherworldly in his qualities as a samurai. What is so wonderful about what Delon does though is this never seems something forced in his performance but rather wholly natural to the character. It also makes watching him a compelling experience as he is spellbinding in his creation of the manner of the samurai. Now this is especially important for the success of the film firstly because he doesn't have much to say at all, but secondly Costello is not necessarily a particularly sympathetic figure therefore it could have been easy to make this silent killer uninteresting. Delon though is absolutely fascinating as he makes every movement as the samurai something to witness.
Delon manages to be especially effective in the scenes where Costello does kill as again his movements accentuate the incisive approach he takes to killing. There is no aggression or pleasure from Delon when Costello kills but rather just a very chilling steely gaze as takes their lives away. It's rather interesting though that this is not quite like say Edward Fox in The Day of the Jackal who also played a professional assassin. Fox played the part of the jackal as a hollow shell of figure who would take on any disguise to make his target, and most of all there was a soulless quality at all times. This is not the case for Delon even though he certainly plays the part of the samurai in a rather cold fashion. Delon though does something else in the role instead and this leads to some of the most remarkable moments during the film. Delon goes about revealing more about Costello than we see, but not for a moment does he change from his intensely subtle performance.
One scene that I particularly liked is after Costello has been injured with a meeting with one of the men who hired him. Costello has to tend to his wounds and Delon somewhat drops the manner of the samurai, almost showing that for the moment the injury has almost snapped him out of his peculiar state forcing him to address something directly that does not require any meditation. It's a striking scene as Delon doesn't show the samurai behavior to be fake, but rather that it is indeed a ritual of sorts for the man. Delon creates particularly powerful scenes though by also revealing that there is a heart in the samurai, and although he kills people for money there is a conscious in him somewhere. It might be rather hard to see but there is evidence of it somewhere.
Delon is extremely reserved in this regard though but surprisingly poignant at the same time. Delon earns these revelations and it seems honest to the character in the way that Delon handles it. He has one amazing scene at the end of the film when it seems Costello is sending another person to their fate. Delon mostly does have that steely gaze again but there is this ever so slight sadness he still conveys so beautifully. It turns out not a sadness for his potential victim but for himself as he surrenders to his fate. It is a perfect moment by Delon and especially notable by just how delicately he handles the scene. The whole performance is a completely fantastic example of truly minimalistic portrayal by an actor. I have to admit to merely loving every second of this performance as he creates such a unique and even oddly heartbreaking character out of the samurai.