I am looking for a name for my fictional, European, mysterious old man who lived roughly in the 1600's to 1800's. I want the name to have plenty of character to it, but easy to read. How should I go about doing this? (I'm not asking for specific name suggestions but a method for finding names.)
Finding the name for you is not what this site is about. Instead I'll tell you how I would find that name.
First, based on the person's character and other traits, as well as his role in the story, I would chose a nationality.
Having limited my choices to names from a certain language, I would then go through lists of names of historical persons: politicians, writers, and so on. These kinds of lists can be found or created (use the "category" function) on Wikipedia. I would then note down every name I found interesting.
Making sure the character's name is dissimilar enough to the names of other characters in my novel, I would then create my character's name from the names I have found and noted down by mixing them to my pleasure.
One: As What says, I would look for names of people of the appropriate sex, nationality, and historical era. For contemporary people, there are plenty of baby name books and the like, both in print and on the web. For an historical novel, I'd look for names of people from that era in discussions of the history of that place and time.
Two: Next, you have to wrestle with the "tone" of a name. Names often give us an immediate image of the person. If you tell me that a character is named Brunhilda, I just don't picture a beauty contest winner. If you tell me her name is Bambi, I don't expect the next sentence to be that she just won the Nobel prize for physics. That's probably unfair stereotyping, but I think we all do it to one extent or another. Unless the point of your story is to challenge that sort of fast assumption about people, you can take advantage of it to help create the image of the character that you want in the reader's mind.
But this sort of thing can certainly be taken too far. I've read stories where the rich man is named Rich Miser and the thief is named Dirk Blackguard and the pretty girl is named Daffodil Sunshine and so on, and after a while it starts to sound more like an allegory or a morality play than a story.
Give your characters names that match their physical or psychological attributes. For instance, in my fiction, I named a man Phil "Potter" because of his "pot-shaped" physique. And a "corny" woman got the name "Cornelia."