A boss you died to 1000 times, an enemy that still strikes fear into your heart every time you replay your favorite game, etc.
For me it's the Blood Starved Beast from Bloodborne. I died to it probably over 100 times my first playthrough no matter how many times I replay the game I still get torn to shreds repeatedly. Honorable mention cazadors from New Vegas
Did you loot the corpse by his spawn? I think he only chases you to the ledge if you steal his dead sister's clothes.
That is probably it actually. I bet that explains some of it anyway.