Here are the doffs listed by name so you can find them on the Exchange:
Very Rare
-
Drolid
-
Moulaysz
-
Phemenne
-
Phutpiel
-
Strerant
-
Tesva P'siv (purchaseable from Fleet Station K-13, but not on the Exchange)
Rare
- Peter Kenneth Daniels (purchaseable from Fleet Station K-13, but not on the Exchange)
Uncommon
- Mark Ford Jones (purchaseable from Fleet Station K-13, but not on the Exchange)
On the off chance you're looking for the KDF officers, here's the relevant wiki page.
Good luck!