Really the three Ex Machina actors all had a pretty impressive 2015.
Domnhall Gleeson : Star Wars: The Force Awakens, The Revenant, Brooklyn
Alicia Vikander : The Danish Girl, The Man from U.N.C.L.E. (+ Burnt, whatever that's worth)
Oscar Isaac : Star Wars: The Force Awakens, Show Me a Hero (HBO miniseries)