Billy the Kid via Wikipedia
I didn't know anything about Billy the Kid except that he was an outlaw. Turns out he was a pretty good guy. Also he was very young.
The first time he killed a man he was 16 and it was self defense. The next time he killed was to avenge the death of his boss who was murdered by crooked lawmen.
When he was finally caught at 21 he was able to escape by killing his two guards. He went back to his home to be around the girl he loved, Paulina. Paulina's brother told the authorities where to find Billy and he was murdered shortly after.
A very compelling story. There is a lot more to it and it's absolutely worth your time. To watch the video and learn more about Billy the Kid check out the video at pbs.org.