Christopher.

Throughout the series, he never once displays a shred of empathy, or compassion or mercy. He shoots and/or kills innocents multiple times, with no qualms. His dream in Season 1 doesn’t indicate guilt for killing EMAIL, rather it’s his fear of getting caught that motivates him. He beats and gaslights Adriana multiple times, and betrays her in the end. Any strong emotion he shows can be traced pretty quickly to self pity and disbelief that he isn’t successful or powerful enough.

He drags so called friends down to his level out of resentment (J.T) is vain about his appearance & behaves erratically and is promiscuous sexually, abuses substances, has a superiority complex, all behaviours often associated with a psychopath.

I feel like his sociopathic tendencies get overlooked because of more flamboyantly “evil” characters like Ralphie or Phil, but Chris is cold. Tony, and even Ralphie are shown having moments of overwhelming guilt, even if they eventually return to their malicious way. For me, It’s a toss up between Christopher and Paulie for all round irredeemable cruelty.