Robert Mitchum did not receive an Oscar nomination for portraying "Reverend" Harry Powell in The Night of the Hunter.
Robert Mitchum's performance as Harry Powell is actually rather against type for Mitchum who specialized as hard but usually decent down to earth protagonists. That is not the case for Harry Powell and Mitchum possibly gives his most stylized performance. Mitchum does not suggest for a moment his earlier and later performances as world weary heroes as this pure evil villain. Harry Powell is a strange man who dresses as a preacher, he has the words love and hate tattooed to each of his hands, and he claims to do God's work. In Powell's mind though God's work mostly is brutally murdering women and stealing whatever necessary to continue his "good works", which causes him to try to find the fortune of a condemned man.
Mitchum goes about making Harry Powell a very unique screen villain and absolutely succeeds in doing so in portraying the different sides to Powell method. On the surface there is that of the preacher which Mitchum to a certain extent portrays as a genuine quality in Powell's character which is part of the brilliance of his performance as Powell. When Powell acts as though he is speaking to the lord Mitchum shows the utmost devotion in his words and is believable very believable as the Preacher. There is the power of belief in Mitchum's performance that shows how deeply his perverse ideas mean to him. Every word that he speaks in his Preacher's voice is that of a true devoted man in every word that he speaks and every hymn that he sings.
Mitchum is even quite charming in his performance when Powell tries to ingratiate himself with the mother (Shelley Winters) of the children and the entire community. There is nothing questionable about this for even a moment because Robert Mitchum projects the false warmth so effectively. Mitchum gives Powell a gentle smile at times and a bright deposition that would likely fool anyone not looking hard enough into thinking that not only is Powell a likable man, but also one who can be believed as the man of God he claims to be. Mitchum is excellent with this because he never goes too far with any quality there is to Powell that it overwhelms the entire creation ever instead bringing every facet of Powell both the truth and the lies vividly to life on the screen.
Underneath the preacher though is actually a very basic psychopath and even the ends of his grand plan is simply to steal money. Mitchum within the preacher is quite chilling in portraying the true nature of the man mostly through his eyes. There is nothing but hate in any scene where he bares witness to any woman giving the slightest hint of sexuality. Although Mitchum makes Powell a colorful man in pretty much every other regard but in this regard Mitchum allows Powell's murderous side to be technically nothing special. There is not anything grand about just the simple evil of a man filled with a personal disgust that propels him to do the most despicable actions which he attempts to defend through his belief that it his duty to commit these murders.
The three layers of the man is what makes this a truly compelling work though by Mitchum as you are always aware of the whole Powell no matter what he may be doing which gives the film a general unease. Whenever Powell is preaching or singing, or being a charming gentleman we know there is that cold unapologetic murderer beneath it all. Mitchum realizes each part so well that the combination is where the horror lies in the film because the killer exits in tandem with charmer and the so proclaimed prophet. He's all at once to use the viewer making every scene have a certain underlying dread. There technically should be nothing scary about Robert Mitchum singing about Jesus but because of the way he establishes Powell it is absolutely frightening.
As I said this is possibly Mitchum's most stylized performance as he does things in this performance that are contrary to the way one usually visualizes a Mitchum performance. Robert Mitchum usually is a fairly restrained performer physically but here he takes a fairly approach with his performance. Every gesture makes as Powell is rather grand in his approach and Mitchum makes it completely work. Firstly the manner matches Powell who has his head in clouds and believes himself an otherworldly crusader, and Mitchum reflects through this manner he takes. More important though Mitchum is incredibly compelling his portrayal of Powell's method, especially the great moment where Powell prepares his knife for a murder and Mitchum shows it as if Powell is finding his inspiration from the heavens above.
The Night of the Hunter is essentially a fairy tale, a very Grimm fairy tale no doubt, with the unassuming two children on the run, the fairy grandmother type figure played by Lillian Gish, and the big bad wolf chasing the children. Robert Mitchum is the big bad wolf, and one could not ask for a better wolf on the prowl. Mitchum has every quality of the wolf from hiding his true nature in his disguise as a good preacher, his dark stature with his eyes that reflect his true purpose, and even the way he screams at the end of the film when himself caught. Mitchum is brilliant in making the wolf for this fairy story in his portrayal of Harry Powell. Robert Mitchum is fascinating every second he is on screen and makes such a strong impact then that his presence never leaves the film making even his silhouette something to be feared.