So, connected to the Forsworn the "Old Gods" are mentioned several times. Does anyone know who these "Old Gods" are, I can't seem to find any good information on it.

Old nordic gods? They're actually aspects of the same Cyrodiilic gods. There are four major pantheons (past or present), and they all have parallels that are too numerous for coincidence.

Alduin (Akatosh), Shor (Lorkhan), Tsun (Zenithar?), Stuhn (Stendarr), Kyne (Kynareth), Ysmir (You The Dragonborn!), Jhunal (Julianos), and a guest apperance from Mara and Dibella (whose nordic aspect names we are not aware of).

Others include the Aldmeri pantheon, which formed part of the basis for the Cyrodiilic pantheon (that and the Nordic pantheon), and then the Yokudan pantheon.

I doubt they are the ones they mean. The "Old Gods" of the Forsworn seem to be something else, partially supported by Yngvar calling them Daedra worshippers.

Probably yet another pantheon of aspects of the same gods. Either that or alternate names for a set of daedric princes they worship.

Unfortunetely since the blasted nords stole our gods from us, we may never truly know who they were....

Molag Bal is probably one, given the location of his shrine. Peryite too.

Wouldn't they just be some derivition of the http://www.uesp.net/wiki/Lore:The_Monomyth duo? Anu-Padomay, Anuiel-Sithis, Ak-El, Satak-Akel.
It was this duality in most myth that gave rise to plethora of new gods that man and mer worship, aka Akatosh and co.

The dark brotherhood still worship Sithis in some ways, Its not a stretch that other groups worship the origional duality.

I had understood that what the Forsworn referred to as 'old gods' were daedra.

Clearly there's something deeply wrong with the Forsworn - they seem to love hanging out with hargravens, and those briarhearts................make the Fiends of Fallout NV seem ordinary..............

i hate the forsworn, they look rubbish and their armour, weapons and places where they live svck lol

but i respect their fighting styles

They're Daedric worshippers.

I figured it was a strange mixture of both aedra and daedra, similar to the khajiit pantheon. They don't necessarily split between the two like most men or mer do. The Reachmen likely dont even call them aedra or daedra, but worship their own aspects and interpretations of them. They also probably worship some strange, primal spirits, perhaps related to natural forces? If you look at Hagravens, witches, and the reachmen's "decorations" everything seems to share the theme of some sort of corruption of nature.

I always figured the Old Gods were a Lovecraft reference, like Hackdirt and the Deep Ones in Oblivion.

Daedra. Molag Bal is probably involved seeing as they love debasing Dibellan shrines and kidnap the new Sybil of Dibella.

I don't think Alduin and akatosh are one and the same. Alduin is a dova, whereas akatosh is a deity who chooses to appear in the form of a dragon if I have that correct...?

They used to be one and the same. The marukhati selectives probably seperated them when they caused the first dragon break.(They wanted all the merish parts of akatosh purged)

So Alduin is a part of akatosh

Trouble is there are two Akatoshes, in a way. There's the original Et'Ada, mirror brother of Lorkhan (they represent/encompass time and space respectively), he is the one the Mer call Auri'El, and there is the Cyrodiilic Akatosh, a mixture of Auri'El and the Nordic Alduin. At least until, as Cecilff pointed out, the Auri'Elic part of the Empire's version of Akatosh was sung out of existence.

As for the Forsworn, my uninformed vote goes for the Daedra, and that is perhaps due to an all encompassing reverence for Padomay (not necessarily Sithis, remember Lorkhan is Padomaic in nature, and the Forsworn may represent men without the civilising knowledge they gained from the Mer. As a Nord looks on a Reachman, they see a similar thing to that which an Altmer sees looking upon a Nord.)