Here's descr_names.txt and descr_names_lookup.txt.

The former is easy to understand: names are sorted primarily by faction, and subdivided into men's first names ('characters'), surnames, bynames and women's first names.

I have no idea how the latter file works though, it seems to have names from RTW and MIITW in a seemily random order. I'd guess that whatever additions/removals/changes you make to one file you make to the other, but I recommend that Tristran doublecheck that.