One of my favorite suffixes is -ster. Its is a fun tale of misplaced gender and reanalyzed forms. In Old English, -ster was used to form the feminine nomen agentis (person who does X, Xer), but French also had a suffix, -teur to form the masculine nomen agentis, and after French crept into England, -ster was reanalyzed as being masculine, so and -ess was added to yield -stress, as in seamstress, which is actually doubly feminine. Some of these earlier -ster words survive as dialect words or proper names: Baxter (bake), Webster (weave), Dempster (deem, judge), deemster (a title in Scotland). Some of the Old English words died out: lærestre 'female teacher', hoppestre 'female dancer', lybbestre 'female poisoner, witch'. And some great ones from Middle English like bellringstre or throwstre. The suffix is usually used with verbs but it can also be used with nouns, like gangster.