Begin the Begin: R.E.M.'s Early Years, Robert Dean Lurie. A band I read everything about. 1984 and the music that entered my life that year truly changed me. But I don't expect anyone that is not a fan of the early band would find it interesting.
Siddhartha, Herman Hesse. It has been recommended to me many times over the years—finally read it. As I mentioned in another comment, it's a good book that younger me might have found more profound. Older me was more or less just nodding my head, "Yep, you'll have to learn for yourself…", etc.
I've been working an analog computer so have read a bunch of old textbooks and such that I have found on archive.org and other places online.
I see quite a few books I purchased this year but have not read. (The Japanese have a word for me.) I should really try to read more next year.