- The scene in "The Moor" where the Prince of Naples shows della Rovere what his father had done to some enemies who'd plotted against him: fed them a poisoned buffet, then locked them into an airtight room, set up to look like the Last Supper. They're still there after decades.
- The Prince (now King) of Naples being forced to give the French King a tour of the famous torture dungeons, knowing he's almost certainly going to be their next victim ( he's right). Made worse for the viewers by the knowledge that all those horrible devices really have been used in the past.
- Cesare killing Giovanni Sforza may be extremely well-deserved, but it's still pretty horrible, especially where his head gets forced slowly forward onto the point of his knife.
- Della Rovere's assassin poisoning Rodrigo at the end of season 2 has a shot him trying to maintain his usual Dissonant Serenity despite going into convulsions while Tears of Blood pour from his red eyes.
- The new King of Naples death by pool of lampreys in Season 3. Granted, the guy was an asshole, but still, not a nice way to go.
- When one of his collection of second sons betrays him Cesare throws him in a sulphur pile and sets him on fire.
Nightmare Fuel / The Borgias