1. X-Men: United - Wolverine vs Lady Deathstrike. I usually give X-Men a pass for this because Wolverine tends to throw himself into these kinds of situations, but anyone could’ve been caught by Lady Deathstrike, and it just happened to be him. She just happened to not have used her claws on anyone else up until their fight, and no one else in the movie suffers similar levels of violence to that magnitude. This fight was so intense that I couldn’t bear to watch it when I was younger.

2. Young Justice, Season 3 - Halo gets fake-out killed by Lobo. This one is really the only case that irritates me because the series had been relatively tame up until this point as far as gore goes, and so they basically used Halo to emphasize how dark and violent they were willing to get by using her as a punching bag of sorts. It was one thing to do it once, but then it becomes a redundant trend with her character.

3. Igor (2008) Scamper - Scamper is a character who was invented by the protagonist and his whole thing is that he’s immortal and doesn’t wanna live. He counts because he’s generally the only character to suffer any lethal consequences.

4. Prometheus, as one of the oldest examples of this trope and an originator of it in a way. Punished for giving fire to humanity, he’s chained to a rock for an eagle to tear out his liver, only for it to grow back overnight and for the eagle to return the next day.

These characters are always the stress test for the levels of violence that the story will go, and often always act as a good indicator for how gory, violent, or dark the story can or will get based on how the story punishes them for being able to survive anything it throws at them.

Other characters might suffer, but the immortal is basically the story’s punching bag for violence and gruesome physical trauma since they’ll be fine after a minute. I have mixed feelings about it because it annoys me when a story abuses it as a trope, but it can be interesting at times.

[Controversial trope] The only character with the healing factor is also coincidentally the one subjected to the most extreme acts of violence that the story will allow