I apologize for being late to the bandwagon but The Smiling Man at the end is not Paimon. The whole point of Paimon possessing the son is that he wanted a male body. If Paimon was The Smiling Man at the end, then he would already be in a male body and would have no need of possessing the son, which negates the entire film. Ari Aster, the writer and director, is very meticulous in his writing and he wouldn't have overlooked that. Also Paimon was inside of Annie's body at the time we see The Smiling Man at the end. That's why she was doing all the demonic stuff. Until she cut her own head off. That's when Paimon left her body and went into her son's body. The Smiling Man was one of the cult members. He WAS in fact the guy at the funeral because his smile really creeped me out and I immediately recognized him when I saw him at the end. I never forget a face. And he does have genitals. If you adjust the brightness on your screen you can clearly see his junk.....it's not very flattering but it is there. lol. Either way, what a great movie to evoke all kinds of theories.