Here's a top of the head list of the most important assassinations of political leaders in America since WWII, plus attempts on the life of Presidents and Presidential candidates, with a rough grouping of the assassins in terms of left, right, or apolitical crazy.

Harry Truman - Left — Puerto Rican terrorists - Left

John F. Kennedy - Left — Lee Harvey Oswald - Left

Malcolm X - Left — Nation of Islam hitmen - Left

Martin Luther King - Left — Conspiracy of white racists and criminals - Right

Robert F. Kennedy - Left — Sirhan Sirhan - Left

George Wallace - Right — Arthur Bremer - Apolitical Crazy

Gerald Ford - Right — Squeaky Fromme — Left or Crazy?

John Lennon - Left — What's His Name - Apolitical Crazy

Ronald Reagan - Right — John Hinckley - Apolitical Crazy