Hello there,

i am not much experienced with modding, so i hope you guy can help me.
I fooled around to some extend with installing mods, and manipulating the game models, and i know how to use 3d software.
My goal is to create a player, that i create in 3ds max and texture it on my own.
I already managed to extract the ingame files/models and import them into 3ds max, but i was never able to find the players head and textures.
So my question is: is it possible to change the players appearence (except for armor) especially the head/face? If yes, how?
I searched google, and many forums, but couldn't find an answer. I mean, it seams to be possible to make a completely custom NPC, but the players face seems to be reduced to the ingame facegenerator.

Well, there are a few limitations to this.

For one you cannot alter "the player" but any of the "races". Before you start a game and select a race the player has no fixed appearance, there's nothing which could be changed from outside.
Then all races share the same body meshes, so getting a different appearance in body-shape between races is not easy to accomplish. I'm not saying it's impossible, it just requires some work-arounds, not rarely involving trickery via scripting.
Plus in Oblivion your body comes with your clothing, so no matter what trick you use to get different body meshes when nvde, once you equip something you'll get the body mesh from inside this (together with all texture issues arising from this).

A race's head has to underly certain factors to be fully functional ingame. You're right, it has to do with FaceGen, but it's not like you couldn't craete a completely custom head mesh. You just need to create the necessary EGM (facial shape morphs) and TRI (facial animations) files along with it. This however is still not very easy, unless you possess the licensed version of Singular Inversion's FaceGen Modeller (or so I've heard). Doing this without the licensed tool is still highly complex. The NIF, EGM and TRI have to match or your face will be massively distorted ingame (like a mess of polygones exploding).
You need to model all morphs and animations (quite a number, around 50 or so) or it will not work, and import/export from/to NIF files directly is no option, because this will inevitably alter the vertex order and the files will no longer match.
Also a face consists of more than 1 meshes. There is the inner mouth, the tongue, upper and lower teeth and maybe even the eyes. All these need to have matching morphs and deformations in matching EGM and TRI files as well. You see how the number of meshes you inevitably have to create keeps rising? Plus you will require HEX-editing some files, or use Scanti's very handy tools, to even create those EGM or TRI files.

The only person I know who ever attempted something like a completely new head mesh modeled from scratch would be ThrottleKitty, just for reference.
There are a few guides available from TK telling how it was done and what's important. Search TK's mods and you will find them.

P.S.: I'm still waiting for the Blender NIF Scripts to get TRI file support as well, because only EGM file support as it is now is useless for creating new head meshes. But once it can import and export both, there'll likely be no hex-editing or other magic required anymore, plus the exported NIF/EGM/TRI files will always have matching structure. All in all the whole ordeal should get way more easy.

thank you for your detailed answer.
so may i sum it up, to see if i understood you correctly? this means, every head in the game is based on the same standard face, and every npc is just some sort of face gen morph based on said standard face/head-mesh. therefore, if i manipulate one head within a 3d program, i may endup creating a mess affecting every character in the game?
the throttlekitty reccomendation looks interesting, thank you.

No, that's not 100% right.
Head meshes are different on a per-race basis. So any NPC of 1 race uses the same head mesh as all others of this race and the difference comes only from FaceGen morphs.
But you can create a completely new head mesh for your own race for example. It's just still a very tedious and complex task.
The mess will not come from the head you're altering affecting all NPCs but rather from altering the head itself, if you're not doing it 100% right (ref. to all the required points in my last post).

If you want to achieve more then you can in face gen, you can also alter the standard face of a race in the Construction Set, in case you did not know. All you need to do is open the race tab of the race you wish to change, then go to the head tab. In there you can model the head to almost anything you wish by the right mouse button. But be careful, in the window you get you do not have a very good outlook at your work so you may as well end up screwing things pretty badly.

It is far easier as it does not require you to make any new models and all the files around this, but it is also more limited. Again as was said, this process alters the head for all the members of the race (male and female), so to avoid this, you would most probably like to create a custom race.