Tear Jerker / Quincy, M.E.

• The ending of season 5's "Unhappy Hour" qualifies. Thanks to computer reconstruction of the crash, Quincy and Asten now have proof that Asten's niece wasn't the driver, meaning the crash wasn't her fault. Unfortunately, while they're demonstrating the results, Asten's niece, having become too overwhelmed with guilt, jumps to her death. Asten's planned speech to the local high school about teenage drinking does not go as planned, he breaks down and throws out his speech, making an impromptu plea to the students to not throw their lives away. The only positive outcome was that a few of the students actually listened to him.
• The ending of "Screaming to the Skies". Not only does Quincy's attempts to get more life-saving apparatus's on airplanes failed, but he is restrained from doing any more about it by a defamation suit by the airline. Definitely one of the most tragic episode endings.