For my Garnia campaign world there was some serious re-imagining of all of the races PC and monster for their origins anyway. Mechanically nothing really changed, since I designed it to be, at first at least, a pretty much "standard" AD&D fantasy world. In Garnia the only sentient race that is native to the world are the elves. Every other race was either brought to the world by the elves through their gate magic technology, years ahead of Stargate I might add; or they were brought in by the forces of evil in an invasion scheme. Now that I think about it that is pretty much what was going on in Q1: Queen of the Demonweb Pits.
Anyway, most of the monster races were engineered by the forces of Evil, usually by whatever demon lord is their master. Yeenoghu for the Gnolls for instance or Lolth for the Drow*. The Goblinoid races were a result of Evil tinkering with a species of humanoids on an evil plane. The Orcs were bred on an evil plane and transplanted late into the setting. The Trolls actually were the shock troops that destroyed the Dwarven home civilization on a neighboring good plane, ergo all Dwarves are refugee descendents, and the Trolls followed them to Garnia before the Elves sealed the gates. This period is known as the Troll war and Dwarven exile in Garnian pre-history.
Only Humans have the capacity to choose alignment in Garnia. Humans come from earth which is on a Neutral plane. They were brought to the Elf home plane by the forces of Evil who were using them as a wild card in their war against the Elves. This turned out to be a mixed blessing (curse?) because Humans destroyed Elven civilization, but then largely chose Good** and took up the fight against Evil where the Elves left off.
So, other than there being magic genetic manipulation to create some of the evil species of humanoids, my primary campaign world of Garnia is largely absent any real remaking or re-imagining of classic D&D creatures. Having said that, I had a Roman empire themed world where the only PC races were Human and Dwarf. We only played there once and I didn't DM. Darryl C. and I had created it together while we were brainstorming some D&D stuff because we wanted to start a new campaign. Darryl wanted to run the initial game because he had an idea for an adventure taking place in a pyramid tomb (that didn't involve mummies). The game went well and my character was, uncharacteristically for me, a Cleric named Gaius Flavius Maximus priest of Neptune. This was the first time I played D&D with Mona, who would eventually become my wife, having only met her once before. The game was pretty good. Unfortunately Jamie W. showed up and managed to quench my enthusiasm for the campaign before I even got my chance to DM an adventure there.
Anyway, the point was that the Dwarves had an unusual racial background in that they were all male, born to human families only in a mountainous region of the game world. They had a natural affinity for metal working and were thought to be the sons of Vulcan. They could become priests of Vulcan only and when they did military service they were organized into their own units. They were all Lawful Good or Lawful Neutral. Usually their mothers died in child birth. There may have been some other quirky, interesting things about them, but I don't recall anything else off the top of my head.
*The Drow are actually a special case because they are a fallen Good race. My cosmology has very definite Good vs Evil element and Evil races are beyond redemption, they have no choice about being Evil, it is inherent. Rarely, an inherently Good race can be corrupted, the Drow are the premier example.
**This may be a result of an inherently neutral species living on a Good plane, the emanations of Good may cause a disproportionate number of Humans to lean in the direction of Good. In real terms it is because as a DM I prefer to run more heroic campaigns and limit the alignments of characters to Good or Neutral; as Evil aligned characters seem to largely be used by immature players that just want to disrupt the game with intra-party conflict, or worse act out rather disgusting fantasies.