The Dangerous Life and Ideas of Diogenes the Cynic

A key greek philosopher everyone knows two stories about, the one with Alexander's shadow and the plucked chicken. This biography did a good job at widening that picture and establishing that Diogenes had a bigger output and reputation - the problem with which is that virtually nothing of that output remains. Thus a lot of the debates surround to what extent the anecdotes and secondary sources should be taken at face value, and the book has a good discussion on the relevant timelines and norms that suggest what could be real. Given how little information from the man himself survived (mostly some aphorisms and anecdotes recounted by others), this was as thorough as you could expect.