Witcher 2 aren't similar to Skyrim or any TES game at all. In fact no other developers make any games like TES as far as I know. If OP is just talking about open world RPGs, there are plenty.
But if we are talking about similarity in gameplay, openness and freedom, Bethesda's games are the only ones. The closest I can think of would have to be Kingdom of Amalur, nothing from past.
In the past there was stuff like Lands of Lore. They were more linear, but also 1st person. The third title was rather open worldy.
Even earlier there was Legends of Valour. It only plays in one city, but it might have been the first 1st person open world RPG. It was great for its time.
There were a lot more games like that in the past ... but they are very old now. They are from the time, when enemies were just 2D bitmaps.
The old Might and Magic games for example ... you had multiple characters in a party, but it was still 1st person.
Then you have games like Gothic1,2,3 and Risen which are open world. Gothic 1 and 2 are some of the best open world RPGs ever created. But they are 3rd person.
Then there are things like the old Fallout games and Jagged Alliance 2, which are open world, but ISO-view.
And of coruse there is Fallout3, which is very much like TES (but gameplay wise worlds better in almost every point). It's just another kind of world.
Oh, and don't forget Nehrim, which is a total conversion mod for Oblivion.