Closed species
I'm not heavily involved in Closed Species communities, and most of the ones I own are just "closed" by way of no longer being in production.
Nicrons, viricrons, holocrons, etc. Any of the 'cron species created by FlamesVoices on deviantArt. Species appears to be discontinued/ no longer in production.
Species made by Spirivern (a friend of mine) on deviantArt. They don't draw as often as they used to, species is closed but possibly not defunct afaik.