Malcom X was a convicted felon and agitator who was semi-famous for being very angry.

He was born as Malcom Little, but changed his surname to X because “some blue-eyed devil named Little had imposed [the name] upon my paternal forebears.”

While he was in prison, Little X joined the antisemitic domestic terrorist organization the Nation of Islam.

Eventually he got in a pissing match with the leader of the NOI Elijah Muhammad. Because Islam is a religion of peace, Muhammad had Little X assassinated.

Source: History Channel and wiki