Here's some of the sources I've seen when working on that topic [1] : Census data, Phone books, Academic bibliographic databases (web of science, pubmed), list of athletes at olympic games, Wikipedia, LinkedIn, ...
Oh yeah ! Onomastics (the study of names) is very cool ! And a nice data point to add to personalized data. I did a project with that a while ago to study discrimination in France (https://namograph.antonomase.fr/) and it worked pretty well as long as you have large samples and stick to distributions comparisons.