I've added five new conlanger types!
Loyalists have one conlang, and probably have only ever made one conlang. They've worked on it for years on end, possibly 10 or 15 years. Maybe they started this language in their adolescence and are in their fifties now. The language becomes elaborate, with a large vocabulary and 100-page grammar, and is as finely polished as a crystal skull with the intricacies, quirks and exceptions to rules that have been given time to develop. As a result of sticking with this one conlang, they usually produce a masterpiece that wins the acclaim of other conlangers, and sometimes even non-conlangers.
Scrappers are the serial monogamists of the conlanging world. They'll get a seed of a conlang in their head, develop a preliminary phonology, toy with the aspects of grammar that interest them, create a few words, (possibly) dabble in giving it a conculture, decide they don't like it, scrap it, and start a new one. Lather, rinse, repeat. One of their conlangs may have only 33 words of vocabulary as of the time it gets dumped, and their vocabularies will certainly never reach the size of Itlani or Talossan. Often they do not have enough grammar to say "The girl ran smoothly past the gate", or possibly even to say "I love you" as of the time they are scrapped. Scrappers might create 50 or even 200 conlangs in their lifetimes, but will never produce anything approaching what a loyalist would create in its scale and depth. They learn a little something from the experience of each conlang they create.
Fillers take a conworld and fill it up with peoples who each speak their own language. This can be a country, a planet, a solar system or even a whole galaxy. If scrappers are the serial monogamists and loyalists are the faithful lovers of conlanging, fillers are the polyamorists. They have many conlangs, often forming conlang phyla with the scale and scope of Indo-European, Afro-Asiatic or Austronesian, with diversity in phonology, syntax and morphology across the different branches and phyla. Since each language has a well-defined role -- being the official tongue of a people in their conworld -- fillers keep all their languages. Some can be more developed than others, even though a filler may create a Swadesh-type list for all of his or her languages, but even the less developed ones will never be deprecated. The final goal of fillers is to finish a world replete with peoples and languages.
Perfectionists have that conlang they've aimed for again and again. They are the gods who create the world, see the world is flawed, destroy it, and try again. A perfectionist's goal is to create the perfect language. Like a scrapper, a perfectionist keeps trying new things, but each sketch is very similar to the previous one, which in turn was similar to the one that came before that one. Each incarnation gets tried under a different (sometimes slightly different) name, but essentially there is one persistent vision in the conlanger's heart. [Thanks to Valosken for suggesting this one.]
Circumnavigators have eyes that survey the whole world when it comes to conlanging. They've created a wide variety of conlangs that they've kept, but not all for the same conworld. Circumnavigators have created fantasy conlangs, alien conlangs, conlangs for Bronze Age peoples, conlangs for futuristic humans, altlangs, micronational languages, personal languages, and jokelangs. They've likely experimented with engelangs (perhaps both a logical language and a philosophical one) and auxlangs (Euroclones and worldlangs) as well as artlangs. They've created at least one highly original experimental conlang. Circumnavigators have often authored visionary and inspiring material about the art of conlanging and the whole philosophy therebehind.
Freelancers will create conlangs for whomever needs them. They might create a conlang or two for an online collaborative world, then help some friends running an RPG campaign create another conlang, and might even be tapped by movie or TV producers to create a conlang for their fictional world. As they conlang for others, freelancers' conlangs are for different conworlds/projects, yet each have a well-defined purpose, and whether they get scrapped depends on what the people they help eventually choose to do with these conlangs. Freelancers typically have a wide array of glossopoetic tools under their belts, painting from catholic phonological, morphological, syntactic, lexical, and maybe even orthographic and pragmatic palettes.
Filmstabbers are the married lovers who unfaithfully go off and see a tempting mistress as the need arises. Like stabbing a few holes in the film over an entrée to let the heat escape while microwaving it, filmstabbers keep to their main conlang (or conworld full of related conlangs) while dabbling with other projects just to release the steam. Want to stick with Butzmazian but can't get that polysynthetic click sketch out of your head? Simple. Create a polysynthetic click language called !Xan/aaxhaapatetl, flesh it out over the next few days, scrap !Xan/aaxhaapatetl two weeks later, and keep Butzmazian all along instead of throwing it out with the bathwater.
Replacers have a bit of filler in them, and a bit of scrapper. Each of their languages has a well-defined role within a conworld, and their eyes are fixed to the same star all the while, but the conlang spoken by a particular conpeople -- or many particular conpeoples -- keeps getting replaced. Similar to TNT'ing an unsalvageable Wikipedia article, a replacer razes the language of the Empire of Samphoria and, after its destruction, erects an entirely new Samphorian language. Unlike with a perfectionist, only the name is the same.
Squirrels chase koi . . . chase squirrels
My Kankonian-English dictionary: 72,000 words and counting
31,416: The number of the conlanging beast!