In 1998, Donald Westlake (under the infamous name, Richard Stark) brought back his heister Parker after a 23-year (or so) absence. By then, I had read all the Parker novels (tracking some of the hard-to-find titles by interlibrary loan).
I never took to Westlake's comic heister Dortmunder in the same way, though I have read and enjoyed several of these books. For me, Dortmunder (and maybe humorous crime fiction more generally) works better in shorter form. The Dortmunder stories, Thieves' Dozen (11 stories!), are pretty great. Dortmunder also appears in a strong (and less slapsticky) novella, "Walking Around Money," in Transgressions (edited by Ed McBain).
Westlake also wrote a series of linked stories about a morose cop, Levine. This collection -- bittersweet, world-weary, bracing -- is really worth reading.
I'm still on my war literature campaign (just read The Thin Red Line -- thumbs up), but I took a break and read Enough, which Westlake called a "two-reeler" (and both "reels" loosely deal with the film industry). The book includes one short novel, A Travesty, and a novelette (?) called "Ordo," which was reprinted in The Mammoth Book of Pulp Fiction (edited by Maxim Jakubowski). A Travesty is a fun, humorous lark about a crime-solving, murderous film critic who is unfairly framed for a murder he commits (think about that?!). "Ordo" is pulpy in its way -- featuring a sailor protagonist and an underage wife (and later starlet) -- but it also has what I might call existential resonance. (And now I've just discovered a French film adaptation, 2004, after I wrote the word "existential." Hmm.) In other words, more Westlake worth reading.