Trills

They are humanoid species that live on Trill. A small number can sustain a symbiont within there body. The result of this symbiosis is the merging of two minds, bodies,  and souls. Also Trill hosts remember things of previous hosts.

Eska

They were technologically advanced. They hunted shapeshifters known as Wraths. Archer gave the Wrath a masking chemical to prevent them from the Eska.

Eska are humanoid. They have large bony ridges that begin at their nose and goes to their forehead. This causes them to have emence eyebrows.