David Strathairn ("Alphas") =
The 12th Governor of New York, United States Senator and the United States Secretary of State under Abraham Lincoln and Andrew Johnson.
(Into the Wild) =
An American journalist and politician.
Jackie Earle Haley (Watchmen) =
Vice President of the Confederate States of America during the American Civil War.
James Spader ("The Office") = W.N. Bilbo &
Tim Blake Nelson (O Brother, Where Art Thou?) = Richard Schell
John Hawkes ("Eastbound & Down" and The Sessions) =
A political operative.
("Rizzoli & Isles") =
An American lawyer and politician who served as Secretary of War under the Lincoln Administration during most of the American Civil War.
(Running with Scissors) = John Hay
An American statesman, diplomat, author, journalist, and private secretary and assistant to Abraham Lincoln.
("Mad Men") =
Ulysses S. Grant
The 18th President of the United States following his highly successful role as a war general in the second half of the Civil War.
("Pushing Daisies") =
An American politician of the Democratic Party and mayor of New York City; he also served as a United States Representative and as Chairman of the Committee on Ways and Means in both the 45th and 46th Congress.
("Boardwalk Empire") = George Yeaman
A U.S. Representative from Kentucky.
David Costabile ("Suits") =
A U.S. congressman, territorial governor of Montana and railroad president.
Walton Goggins ("Justified") =
A U.S. congressman.
(The Last King of Scotland) =
Corporal Ira Clark
A soldier and former slave before the Civil War.
Julie White ("Go On") =
Elizabeth Blair Lee
An American woman who lived through the American Civil War, and wrote hundreds of letters describing the events of the times to her husband, Samuel Philips Lee.
S. Epatha Merkerson ("Law & Order") =
The wife and former servant of Thaddeus Stevens, a Republican leader and one of the most powerful members of the United States House of Representatives.
Dane DeHaan (Chronicle) & Lukas Hass = Soldiers
*In the event any of this is historically inaccurate...blame Wikipedia.