(written from a Production point of view)
This page contains information regarding material for the upcoming Star Trek film, and thus may contain spoilers.
Benedict Timothy Carlton Cumberbatch (born 19 July 1976; age 39) is an English actor who plays the role of of a character named "John Harrison", the villain in Star Trek Into Darkness.  In February 2012, several images from the filming of a fight scene with Zachary Quinto appeared on the web. 
Born in London, England, Cumberbatch is best known for his portrayal of Sherlock Holmes on the BBC drama program Sherlock, which premiered in 2010. He began his professional acting career on the stage in 2001, making the transition to television and film a year later. He was lauded for his performance as Stephen Hawking in the 2004 BBC drama Hawking, which featured his future Star Trek co-star, Alice Eve. He and Eve again appeared together in the 2006 feature film Starter for 10.
Cumberbatch has worked with two other actors who played villains in Star Trek films. He starred opposite Tom Hardy (Shinzon in Star Trek Nemesis) in the 2007 TV movie Stuart: A Life Backwards and both appeared in the 2011 adaptation Tinker, Tailor, Soldier, Spy. Cumberbatch also appeared with Eric Bana (Nero in Star Trek) in the 2008 film The Other Boleyn Girl.
Cumberbatch's other film credits include his critically-acclaimed performance as William Pitt in Amazing Grace (2006), Paul Marshall in the 2007 adaptation of Ian McEwan's novel Atonement, and as Major Jamie Stewart in Steven Spielberg's War Horse (2011). He'll also provide the voices of Smaug the dragon and the Necromancer in the highly-anticipated three-part adaptation of J.R.R. Tolkien's The Hobbit (2013), opposite his Sherlock co-star Martin Freeman.