15MICHAEL ROSENBAUM - LEX LUTHOR
One of the obvious changes Michael Rosenbaum made when he took on the role of Alexander "Lex" Luthor for Smallville in 2001 was to shave his head. After all, would fans accept a Lex Luthor with a full head of hair? As evidenced by Batman v
Superman, not really.
Rosenbaum embraced the character and portrayed him in a new light by making him both the greatest enemy to Clark Kent and his most trusted friend and confidant... at least for a while.
Rosenbaum didn't remain with the cast throughout the entire series run. He left the show after seven of its 10 seasons but returned for the series finale to reprise his role.
These days, Rosenbaum has let his hair grow out and is rocking stubble, which somehow makes the actor look a little younger today than he did 16 years ago. He has been working steadily since his time on Smallville and most recently had a role in Guardians of the Galaxy Vol. 2.