It has appeared as a trope in many Hollywood movies and novels, where a justice leaning the opposite direction of the current sitting president is assassinated whereby a new justice can be appointed that will shift the winds of the court.
There are several conspiracy theories about Scalia’s death and lack of autopsy suggesting there may have been foul play.
The closest such attempt I found was on Justice Stephen Field’s life before he was appointed to the Supreme Court. In 1889, while Field was a Federal Circuit Court Judge, a former California Supreme Court Judge, David Terry, attempted to kill Field over his ruling in Terry’s divorce case. Terry was shot and killed by a US marshall, Field’s body guard.
So have there ever been any credible assassination attempts on a sitting US Supreme Court Justice?