The idea of "re-skinning" comes up pretty often, where you take a stat-block of a well known creature but alter the way you describe it, maybe change a few minor things like damage type, and have a whole new monster. What I think comes up less often is the idea of re-loring a monster: that is, giving a well known staple D&D monster a totally different backstory, place in the world and lore, but keeping it pretty much as is otherwise.
As an example, in one of my home brew worlds, ogres were explicitly the sons of hags ("bog witches" in this setting) who had seduce via shapeshifting local lords and such. in this setting, even bastard sons could claim their inheritance and these hags would create heirs so they could ruin the lords and their lands, putting their violent and deformed offspring on the High Seat.
In another setting, gnomes and goblins were the same fey "species" -- but if they were malevolent, their form changes to goblin and f they were benevolent their form changed to gnomish.
What kinds of re-loring have you done in your games and campaign worlds? Why? That is, what was your motivation for doing so? For example, I once decided to make succubi cosmic psycho-therapists just to combat the "evil hawt woman" trope; they were able to control minds and such because they were getting in there and helping put things back in order.
Do you have a favorite bit of re-loring someone else did, fan or pro?
Thanks.