-monger, as in costermonger, fishmonger and scandalmonger. [The latter seems to be a coinage, no doubt semi-humorous, from the early 1700s.]
-master, as in postmaster, stationmaster, schoolmaster, quartermaster, toastmaster. [Maybe some of these are less well known in the US than in the UK. Postmistress and schoolmistress used to be at least as commonly used in the UK as their male equivalents, but have an old-fashioned ring now.]
-er, as in wheeler, jeweller, glazier, grazier, butcher ...
-ist, as in cyclist, psychiatrist, motorist.
No doubt my last example isn't quite in the spirit of the question...
-worker (dockworker, lineworker, coalworker, metalworker, glassworker, ironworker) is an element that identifies people who work in a particular place or with a particular material.
Some (like dockworker) are compounds with worker. Others (like ironworker) may have been formed from ironwork(s)+er (see Merriam-Webster, which lists ironworker under ironwork).