Alien races you would like to have seen expanded upon?

One thing I dont like with startrek is the alien of the week menality were they meet a cool alien and move on never to revist them. In some cases ok fine but there were some really cool aliens I would have loved to see be expanded on.

For me:

Tamarians: I would love to see what develped after first contact with them.

Sheliak: Who were they? They seemed far diffrent from the useal humanoid aliens we get.

The aliens from schisms: Why were they abducting people? Again who were they?

 

Delete this as expanding it to other series and putting it on Gennral forum.