6. John C. Reilly
This character actor's first lead role was in Anderson's debut drama Hard Eight, playing a down-on-his-luck gambler; when Anderson moved on to his next film, he used the actor in an entirely different way. In Boogie Nights, Reilly was the cocksure Reed Rothchild — goofy porno actor, erstwhile magician, coked-up comic relief and adorably loyal sidekick to young superstar Dirk Diggler. Then, in Magnolia, he wound up as good-hearted, devout, lovesick cop, in the film's one storyline that suggested there might still be hope for humanity. No matter the part, Reilly seems to bring real warmth to these characters; we want him to be okay in these dark, dangerous worlds that Anderson spins around him.