Demogorgon-dog is shot. It doesn't look like a dog but is heavily implied that it is a dog. A "demidog" is killed in the first 10 minutes of the first episode.
The people who die by Vecna's Curse have their eyes sucked into their head, leaving empty sockets. This is shown closely for almost all Vecna related deaths.
All of Vecna's Cursed victims are 17-18, with the exception of one 14 year old, who technically doesn't die, but is severely harmed. Several children die in the Hawkins Lab massacre, and while we don't see any of them die, the aftermath is still quite graphic.
Chrissy Cunningham is heavily implied to have an eating disorder, and there's a scene of her throwing up/purging (non graphic). There's also a few instances of her mom pressuring her into losing weight and calling her fat that we see in her Vecna trances. This isn't mentioned at all or referenced after the first episode.
Arguably. One character chooses to sacrifice themselves to protect others, and while it's portrayed as heroic... 🤷. Another character also chooses to sacrifice themselves and talks about having suicidal thoughts right before, but they technically don't die