The super mutants from the first fallout are so interesting, maybe not the best in terms of morals (hell in the first game the master intended to make the human race extinct by castrating them) and whilst he may have not had much screen time, The Master is on the best villains because he's given so much character in the few moments you have with him, and the addition of character in the sequels, except 3 and 4 who just made them into orcs instead of super strong/intelligent humans