Becoming the first man in history to win three Oscars for Best Leading Actor in 2013, when he won for his performance in Lincoln. Even more impressive given how few films he's been in given how picky he is.
His performance as Lincoln is considered by historians to be akin to someone going back in time and doing a documentary on the real Lincoln, bordering at times on the uncanny and it almost seemed like the real-life Lincoln had returned from the dead, so thorough was his immersion into the role. Lewis researched the part for a year, read over a 100 books on the man and nailed the accent, the body language and other details present in many descriptions of the period. Many consider it the greatest performance of any historical figure in film history.
His incredible versatility makes him unlike any actor in history. From staid romantic Newland Archer to violent sociopaths (Bill the Butcher, Daniel Plainview), and from there he played Lincoln, which was a sharp divergence from Daniel Plainview.
Many of his Method Acting attempts seem unnecessarily extreme, but there's something to be said for a guy who built his own house using period-appropriate tools, as he did for the film version of The Crucible.