Star Trek III: The Search for Spock - The Fall of Kruge

Commander Kruge takes on Admiral James T. Kirk at the climax of Star Trek III: The Search for Spock

Star Trek II: The Wrath of Khan - Death of Spock

With the warp drive damaged, the Enterprise will not be able to escape the explosion of the Genesis Device. Spock goes to the ship's engineering section to restore the warp drive exposing himself to high levels of radiation. Spock restores power to the ship allowing the Enterprise to reach a high enough speed to avoid total destruction.