77. Zosia Mamet
Biggest accomplishment this year: Consistently stealing scenes in the altogether uneven second season of HBO's Girls
Known primarily for her role as the hyperactive Shoshanna Shapiro on Girls, Zosia Mamet has begun to establish a foothold as an up and coming young actress. She's been roundly praised for her work in the increasingly dark second season of Dunham's show, giving her seemingly shallow and superficial character a surprising amount of depth. New Yorkers can also catch her starring in Really, Really, an off-Broadway play based on Shakespeare's Much Ado About Nothing that inspired Mamet to dye her hair a striking shade of blonde.