Robert De Niro did not receive an Oscar nomination, despite being nominated for a Bafta, for portraying Jimmy Conway in Goodfellas.
De Niro carries himself particularly well in the scenes where he takes the young Henry as well as the young Tommy DeVito under his wing. De Niro carries himself with almost a fatherly grace as he shows the boys the ropes even more as he runs his various criminal operations. De Niro shows Jimmy to seem like such a generous man at first as he has people doing exactly what he wants them to do for him, but we seen soon enough that it is hardly all there is to Jimmy. The first scene that perhaps makes the abundantly clear is when someone who owns Jimmy money keeps dodging the questions and even openly acts defiantly towards Jimmy. De Niro is great in the scene as he pretty much breaks down to exactly what Jimmy is behind his nice suits and his genial demeanor to those who serve his interests, which is a thug. De Niro plays it in a particularly uncompromising fashion as he shows Jimmy to bluntly brutal in the way he roughs up the man for paying up. There's no warmth, not even any reserve, its a direct violent outburst from a man who's simply not getting what he wants out of him.
De Niro, Liotta, and Pesci as Tommy are particularly good together in just portraying the camaraderie between the three. They are terrific together in bringing such an authentic feeling ease they have together as the three enjoy all their life has to offer. They are good in their moments of enjoyment, even when ribbing one another over slight things, and what so remarkable is how they show essentially the little things in the life of the wiseguy. De Niro and Pesci are very interesting together in that as Pesci realizes the overt psychopathy of Tommy while De Niro is quite good as he shows that Jimmy really not far from Tommy in terms of nature he just happens to be better at utilizing his violent tendencies in a "useful" fashion. De Niro brings that same sort intense violent glee along Pesci when Jimmy goes about helping Tommy kill a mobster who insulted Tommy. De Niro and Pesci together are brilliant in the way they realize the very dark nature of the mobster as a man by doing it in such a convincing and casual fashion. They really are quite evil, they just happen to be able to get along in a normal way simply because of their position in the mob.
One of his best scenes is when it appears as though Tommy is about to be a made man, something Henry and Jimmy can't become because they are not pure Italian. De Niro is outstanding in the scene as he manages to create some sympathy for the psychopathic Tommy through first bringing such genuine enthusiasm as he waits for the news only to bring such honest grief when things don't go as planned. That's what so good about De Niro here as he so eloquently is able to believably show all these different facets of Jimmy while keeping him as one man. In addition De Niro actually creates some of the most chilling moments because of his creation of Jimmy's nature like this. The section that of the film that follows most closely on De Niro is after a gigantic heist masterminded by Jimmy, but for some reason every man on the job wants to try to screw up afterwards. There is one amazing moment from De Niro, as it's a silent reaction shot, but in his face you can see his mind planning the death of everyone who is trying to screw up his idea for the money from the heist. De Niro makes Jimmy especially dangerous through the way he specifically conveys his maliciousness which only makes itself known when completely necessary. The scene where he asks Henry's wife to look a dress, although clearly planning something else for her, is particularly unnerving because again De Niro keeps up a generous spirit with Jimmy while in those eyes there's that glint again of his true nature. This perhaps De Niro's best collaboration Scorsese as he knows exactly how to work within the film. He allows other actors to shine when they have their moments, amplifying their work with his own assured performance, giving so much more texture in certain scenes just by sometimes being in the background. When it is his time though De Niro delivers every moment and creates a fascinating portrait of Jimmy Conway.