Using the Appearance Preset Tool and the debug menu for dark souls remastered, I extracted the appearance of some NPCs.
As the Appearance Preset Tool can be used for both versions, the appearances are compatible with PTDE and Remastered.

Special thanks to BobDoleOwndU, for creating such a great and useful tool.
(as a personal request, if this tool also saved the inventory and stats, it would be perfect)

Remember that whenever you choose an appearance, you must reload your character.

List of NPC appearances:

-Anastacia of Astora
-Big Hat Logan
-Black Iron Tarkus
-Crestfallen Merchant
-Crestfallen Warrior
-Crystal General or Warrior
-Darkmoon Knightess
-Domhnall of Zena
-Dusk of Oolacile
-Griggs of Vinheim
-Havel, the Rock
-Ingward
-Kirk, Knight of Thorns
-Knight Lautrec of Carim
-Laurentius of the Great Swamp
-Maneater Mildred
-Nico of Thorolund
-Oscar, Knight of Astora
-Oswald of Carim
-Paladin Leeroy
-Patches
-Petrus of Thorolund
-Quelana of Izalith
-Rhea of Thorolund
-Rickert of Vinheim
-Shiva of the East
-Shiva's Bodyguard
-Sieglinde of Catarina
-Siegmeyer of Catarina
-Solaire of Astora
-Undead Prince Ricard
-Vince of Thorolund
-Witch Beatrice
-Xanthous King, Jeremiah

Let me know if there is any error.

The path to see the appearances of the NPCs in the debug menu (keep in mind that applying the appearances also overwrites the inventory and stats, so be careful):
-[GAME](19), [Game Data](29), [Change Character Param](314), A long list will appear, try each one until you see a known NPC.

If there are any NPCs that are not on the list it may be for the following reasons:
-I may have skipped it.
-May not be a human sized NPC, like Andre for example.
-It can be some NPCs without their own name (in which case I do not intend to add it, examples of this: the seven members of the Clan of Forest Protectors).
-It can be an NPC that does not have a programmed appearance itself, such as Ciaran, Chester, the Daughter of Chaos or the two Darkmoon Soldiers.

To consider:

Although the Appearance Preset Tool does a very good job of extracting the appearance of the NPCs, some of them have physical combinations that are not within the character creation options, so when you reload the game the NPC's physical appearance will be adjusted to the chosen in character creation window, one of these NPC is Solaire, you may think that his physique corresponds to the "Large Upper Body", but in reality it is a combination between the "Average" physique with the torso of the "Large" physique and so there are other NPCs with unique combinations, my recommendation is to simply put an average physique, if you don't want to complicate things too much, but if you want to be a little more detailed, try to find the physique configuration closest to what you think the NPC has.

The appearance of Anastasia of Astora is an alternative version that is still in the list of NPCs unlike her current model, which is different from that of a normal NPC.

I decided to add Shiva's bodyguard, because I consider him to be a unique NPC, even though we don't know his name.

I have doubts about whether to add one of the members of the Clan of Forest Protectors, specifically, the one with black bow of Pharis and Pharis's Hat, since she doesn't have a name, she is just a hunter who wears some of Pharis' equipment. So, what do you think, should I add her?