I think I'll start a slight scandal by suggesting the felinoids depicted in "New Earth and "Gridlock". Since late 1982 (after seeing Paul Schrader's lurid remake of "Cat People" which awakened something deep within my id), I've always wondered how Lt. M'Ress (from the animated Star Trek) might have appeared in live action format, and seeing Novice Hame (the "cat" nun who cared for the Face of Boe) gave me a possible solution. Seriously, the way the makeup team was able to apply actual "fur" to the appliances rather than just painted patterns, was truly amazing and better done than a fair number of big budget movie designs.
Hame was a sympathetic character who got a bad deal (I gathered she honestly didn't know what her "sisters" were doing and got arrested unjustly), so I was thrilled she was revealed as a heroine in her second appearance. Plus, Brannigan was just a trip, a likabe, funny fellow from start to finish. Not to mention his "children" were completely heart melting. "Mamma!" Indeed!