Way back when, I complained about how fantasy (and sci-fi) writers have it easy--they can usually just make up a name. Of course, fantasy folks are the type of people who are making up whole worlds, which I stink at, so it's not really like I want to BE a fantasy writer (sci-fi, maybe), but I do envy their ability to go with whatever name suits them (never mind I'd be no good at coming up with good names anyway). And of course, people who write in modern times can use whatever normal name they want, or abnormal if they want.
Not historical fiction people, who don't even have a cool way of saying what they write in a short manner (I vote his-fic or hi-five). If they're like me, and I think most are, they're chained to what names were used in their time period, and if they're especially picky, what nations were using said names.
Thank goodness for Names Through the Ages by Teresa Norman. With this tool, I've been able to put the Historical Accuracy Demons to rest. I don't have to find it another book from the same time period (good luck with THAT) or worry that it might be wrong even if I think it sounds okay. This book has several lists of names--English, French, Welsh, and at least one I'm forgetting--in several different time periods. The lists are prefaced with a brief explanation about what was going on in that country at that time, including why names were changing, if they were.
I love this book (here's an Amazon link), because it doesn't look as suspicious as some of the things that come up online when you search for stuff like that. It also has alternate spellings of the name, if you have fantasy leanings and kind of want the name to look, well, not normal. Surprisingly, I don't OWN that book, mostly because I'm cheap. I do happen to recommend it everywhere, though, so that ought to make up for it! I usually double-check meaning on babynames.com because sometimes they disagree, and babynames will tell me the origin of the name, which is nice. (When you get to the 13th century, the Saxon and Norman names have all muddled together, and the list for that century in England doesn't specify which is which). Actually, when trying to be very specific about origin, I try punching in a name to as many search engines as I can, just to be sure. As in the complaining post I linked to, sometimes they'll all disagree and that's annoying...
Now, what to do when you've run OUT of names is something I haven't encountered, but have felt like I have. All of the male names I LIKE from my list in history are pretty much already used, so I really do express great joy when I find out that I need a new female name. There are already duplicates from my (bad) fantasy and my (better) hi-five, and I don't want even MORE duplicates between the books in what is becoming my Sherwood series.
Speaking of Sherwood, there's a whole 'nother monster one must deal with when writing Robin Hood retellings...I should compose some thoughts about that!
P.S. I'm not so sure about how this Operation: You thing is going to work out...I might end up with not enough material! I'll keep trying, though. I'm beginning to construct a page on historical fiction (and Robin Hood) resources.