For years one of my favorite authors has been Thomas Sowell. What he writes, I'll read, whether it's a magazine article, a book or a column. Some of his best are "A Conflict of Visions", "Migrations and Cultures", "Ethnic America", "Knowledge and Decisions"....
Another favorite is Peter Huber. He is a lawyer and an engineer who has written on many topics of interest to me. Two of his best known books are "Liability - the legal revolution and its consequences" and "Hard Green".
For management, there's Peter Drucker. I don't know if he's still writing or not - he's in his 90's by now. He started writing about management before it was known by that name. About anything he writes is excellent.
Then there's W. Edwards Deming, Daniel Boorstin, C. S. Lewis, George Gilder, William F. Buckley, Robert Heinlein, Ayn Rand and Paul Johnson. Lesser lights are Michael Fumento, Mark Kurlansky, James Burke, Ronald Radosh, David Horowitz, P. J. O'Rourke and Christopher Buckley. Well, alright, I like Kurt Vonnegut, but I'm still waiting for him to grow up politically.
About the one common thread among the above is that I discovered them all after college. None of them were required reading. Many of the above had not produced much by the time I got out of engineering school, but that still leaves Drucker, Boorstin, Lewis, Heinlein, Vonnegut and Rand.
That's ok. At least I had a job when I graduated.