–ician

academician, beautician, biometrician, clinician, diagnostician, dietician, econometrician, electrician, geometrician, logician, magician, mathematician, mechanician, metaphysician, metrician, mortician, obstetrician, optician, patrician, pediatrician, phonetician, physician, politician, pyrotechnician, rhetorician, statistician, tactician, technician, theoretician.  (I don’t include Phoenician.)

–eer

auctioneer, balladeer, buccaneer, cannoneer, caravaneer, charioteer, engineer, fusileer, gadgeteer, marketeer, mountaineer, musketeer, mutineer, pamphleteer, pioneer, privateer, profiteer, puppeteer, racketeer, rocketeer, sloganeer, sonneteer, volunteer.

–ologist

anthologist, anthropologist, apologist, archaeologist, Assyriologist, astrologist, bacteriologist, biologist, craniologist, criminologist, cryptologist, cytologist, dermatologist, ecologist, Egyptologist, embryologist, entomologist, etymologist, geologist, gerontologist, graphologist, gynecologist, hematologist, herpetologist, histologist, ichthyologist, ideologist, immunologist, kinesiologist, metagrobologist, meteorologist, metrologist, mixologist, mycologist, myrmecologist, mythologist, neurologist, odontologist, oenologist, oncologist, ophthalmologist, ornithologist, paleontologist, pharmacologist, phonologist, phrenologist, physiologist,  proctologist, psychologist, rheologist, Scientologist, semiologist, serologist, Sinologist, Sovietologist, Sumerologist, Syriologist, teratologist, theologist, topologist, typologist, urologist, virologist, zoologist.  (In case you were wondering, a metagrobologist is an expert or specialist in puzzles.)

–ier

bombardier, brigadier, cashier, cavalier, financier, fusilier, gondolier, grenadier, sommelier. (There are surely more of these.)

–alogist

From analogy, genealogy, mineralogy, we have analogist, genealogist, mineralogist; but despite mineral/mineralogist, we have criminal/criminologist.  Are there other –alogists?

Note: Some previous Gambits columns have included –eer words, or –ology words, from different perspectives than the present column.