Of all the scholarly books on opera that I've found over the years, Joachim Kaiser's 1984 Who's Who In Mozart's Operas: from Alfonso to Zerlina is by far one of the most interesting. It's a mini encyclopedia of every character from all of Mozart's major operas, featuring descriptions and analyses of every single character: small ones for the minor characters, longer and deeper discussions for the major characters. While other books I've read have offered character analysis within their discussions of the operas as a whole, or else have been devoted to a specific subset of characters, no other book has been as exclusively devoted to character analysis, or as willing to examine even the most minor characters.
