John Wilkes Booth was the assassin of President and anti-slavery liberal Abraham Lincoln. He was an angry copperhead aka "peace democrat" (when that meant "pro slavery", of course). Booth was also an actor who sometimes found it difficult to tell the difference between stage drama and real life. At that time the Republicans were far more anti-slavery and liberal than the democrats and many Southern Democrats later became KKK members.
Booth supported the Confederacy in the American Civil War and hoped killing Abraham Lincoln would prevent freed slaves getting the vote, because in the mind of a conservative, nothing is worse than giving minorities civil rights. This is why we have/need (depending on where you live) gun control. Just look what happens when you "give the wrong person a gun."
Booth shot Lincoln at Ford's Theater on April 14, 1865. Then Lincoln died the next morning on April 15, 1865 at the Peterson House because doctors tried to remove the bullet, but suddenly they had failed to remove the bullet. Booth escaped using a password TB Road. Then Booth's broken leg was treated and then he hid in a tobacco barn with an accomplice called David Herold. When Union troops cornered Booth and Herold there David Harold surrendered but Booth remained in the barn. Then one of the detectives went around the back corner set fire to the barn in order to flush Booth out. 
Despite orders to capture him alive, Booth was shot by Boston Corbett, a religious fanatic who said God told him to kill the assassin. Then Booth died on April 26, 12 days after he had killed the president at Ford's Theater. The assassins were guilty and faced retribution. Many people who had known Booth identified the body as Booth's but later a rumor arose that the man shot wasn't Booth, see below.
In the book, The Escape and Suicide of John Wilkes Booth, Finis L Bates wrote that a man named John St Helen confessed " The name is not John St Helen it's really John Wilkes Booth, Assassin of President Lincoln,  son of Junius Brutus Booth, who was named after Marcus Junius Brutus, the Assassin of Julius Caesar, dictator of Rome. Whether this story should be taken seriously is controversial. If Booth escaped a great many people who identified the body of the man shot in the barn Lied.