* AcceptableEthnicTargets: Spenser and Hawk have a long-running penchant for making fun of one another's ethnicity, with Susan, a self-described "Jewess from Swampscott Massachusetts," periodically getting in on the action (and making her and Spenser an example of IrishmanAndAJew). Any friend of Spenser's who has a sense of humor is equally likely to mock and be mocked in turn, particularly Chollo.
* BrokenBase: Spenser's fanbase skews older, so there isn't a great deal of discussion of it online. That said, Susan is a reasonably controversial character, owing mostly to Spenser's near-constant adulation of her in the narration.
* EnsembleDarkhorse: The tv series made Hawk into one, it even led to his own short-lived spin-off.
* FanonDiscontinuity: It is a common opinion that after a certain point, Parker went on creative autopilot and the books began to suffer for it. Where that point is, on the other hand, is a subject of some debate. ''Rough Weather'' and ''The Professional'', the last two novels before Parker's death, are widely considered to be the series's nadir, but some fans will place the point of no return - the point where a fan would perhaps do better to pretend that the books ended before then - as early as ''Chance''.
* GeniusBonus: Any given one of Parker's books is a mixed bag of references to film, poetry, history, and theater, to the point where the now-defunct Spenser fansite "Bullets and Beer" took a lot of time and effort sorting through it all.