- When the spider crawled out of that guy's... wart... things...
- When Alex stuck a needle behind that kid's eye.
- The scene leading up to Nick Hanscomb's blown artery, while Lexie is in the room. You know it's coming from minute one, but the tension is no less unbearable.
- Not only was the guy with the live bomb inside of him which from start to finish was terrifying, but also the episode where Bailey is operating on a patient and she wakes up. The poor woman was scared to death and freaking out any time Bailey went near her, and you could tell it affected her too.
- That episode when Dr. Shepherd, Sloan, et al. need to split a teenager's lower face so they can access a large bony tumor located at the base of the kid's skull and upper spinal chord. Even Callie is disturbed by how much pain would be caused by breaking the jaw, which is only part of the horrific procedure. Meredith calls it decapitation.
- Cristina's description of her, Meredith, Derek, Mark and Arizona's time in the woods especially the part about the animals fighting over Lexie's corpse. shudder
- Cristina describing the death of her father to Hunt, her trying to hold his chest closed to slow the bleeding and she felt the moment he died when his heart stopped and she was only nine when it happened.
- Derek's And I Must Scream moment, when he's fully aware of the doctors' clumsy attempts to save him but unable to correct their mistakes — he all but flat-out says that he could have saved himself if he was somehow his own doctor. Given that he actually does die and it's not one of the show's classic fake-outs or Disney Deaths, it's pretty chilling, particularly when you add in the whole wife and two — that is, three — kids thing.
- The woman that fell in razor wire. if that's not bad enough she woke up in the trauma room, by god her screams and the way she fruitlessly to escape only to injure herself more, and her screams by god, I can sometimes hear them.
- The idea of George getting dragged under a bus down the road. That, and the fear Callie was put in: she's the only one who knows what to look for but is horrified at having to.
- Being Kepner trying to assist in surgery when you have Cristina monotonously reciting the details of a fatal surgery over and over. Morbid? How about when it's at the request of the dead patient's widow, who's leading the surgery. It's chilling, especially with how blasé Teddy is about hearing it.
- After the plane crash when the doctors are all at Boise and need to be taken to Seattle it's explicitly stated that whilst a ground transfer would be best for Meredith, Cristina, and Derek (and Lexie), because of Mark and Arizona's conditions they need to be airlifted. Imagine being Callie on the receiving end of that news, especially with Sofia.
- Callie's shutdown reaction when Karev bursts into the OR to announce that her seemingly fit wife just crashed and is well on her way to clinical death. And she couldn't move because she was stitching the nerves in Derek's hand. Basically Callie in S09E02 goes through Adult Fear and BSOD's more than one person should be able to handle without nightmares.
Nightmare Fuel / Grey's Anatomy
Some of the injuries suffered—particularly those of the periodic disaster episodes—are truly horrifying. Then, there is the Season Six and Eight Finales, where all hell breaks loose.