A conlanger is a person who invents constructed languages (aka conlangs).
Individuals who have been hired to create languages.
Conlangers who have created languages intended for international communication.
Conlangers whose work has been published in books or other media that they created:
Conlangers whose languages are neither international auxiliary languages nor part of popular media, but are nonetheless significant among enthusiasts, have amassed a notable amount of speakers, or do not fit in other categories:
Toki Pona, a minimalist language which has gained a large following and several publications over the years since its creation in 2001.