Richard Herd as
Elijah - the way he alternates between ruthless, uncompromising and absolutely chilling when he issues his commands, greedy and downright infatuated when he speaks of the Sierra Madre and the moments when you can hear echoes of a different person, an old man who's beginning to feel his age (if you listen in on his radio frequency), is simply brilliant! His voice acting is part of the reason Elijah is one of my all-time favorite Fallout characters and definitely my favorite Fallout antagonist
Jason Spisak as
Vulpes Inculta - my second favorite, his voice conveys a perfect mixture of cruelty and furtiveness, which fits the character so well.
Laura Bailey as
Christine/Vera Keys - Her voice *IS* Christine's as far as I'm concerned, and the recordings of Vera's final moments as played back by the holograms in the Suites are some of the creepiest and most emotionally-charged moments in Dead Money, for me.
Rachel Roswell as
Cass - she portrays Cass perfectly, when I first heard her speak it felt completely believable and in character.
Dave Mitchell as
God - intelligent, calculated, disdainful, full of anger (another DM character, heh, but like others I think the voice acting in that DLC was top notch)
And I could go on
I enjoyed most of the cast from Old World Blues as well, especially the Think Tank, Muggy and Toaster.
I can't think of anyone I absolutely hated, but Benny's lines felt somewhat forced to me, and some of the generic characters sometimes spoke as though reading off a script, for sure.