The 'elements' or whatever they are from Sapphire & Steel! By nothing more than writing, atmosphere and acting they are the most other characters I've ever come across and the whole show provides an outsider POV on humanity. They exist, they come from somewhere, they go somewhere, they had beginnings of some kind, they do what they do and they're fascinating, but a mystery to humans and to each other. They say they're not alien as such, though, either. ("Only in the non-terrestrial sense.") They are probably anthropomorphised metals, alloys and minerals in some sense, maybe? Steel says his origins are postive but inexpressible. Sapphire can't imagine him having origins. Steel can't imagine Silver having a beginning, either. They all seem to be telepathic, and they each have abilities that relate to the metal/alloy/mineral they call themselves. They exist to fix time when it breaks. They have probably existed for centuries. Probably. They have freedom, of a sort, but are sent by something or someone. They have feelings and relationships (whatever form that takes) and even gossip sometimes, but they are the most beautifully other and mysterious characters I've ever come across. When they do more human things, they almost 'play' at it & seem amused, making them never more alien. My biggest regret about the series ending is that we didn't get more Elements, which we probably would have done if it had even one more serial, which is why I love OC element fic. (OCs are Ok in this fandom! XD)

Sapphire:

Sapphire senses and sees things.

Steel:

(Steel does not: eat, sleep, drink.)

Silver:


(He makes things sparkle and glow. It comes naturally.)

There's also Lead, but I haven't made gifs of Lead. Assignment 1 is very green and brown, lol. I must tho.

Lead:

Steel is not allowed to take his temperature to below freezing without Lead around to warm him up after!

I'm also very fond of D84 from the Doctor Who serial "The Robots of Death" who is Best Robot. ("Please do not throw hands at me!")