Did either "Tom Corbett, Space Cadet" or "Rocky Jones, Space Ranger", feature a "resident alien"? Both of those series heralded from the 50s.
I'll do a lil' research.
Follow-up: I guess I was "mis-remembering" aspects of Tom Corbett. That series featured Astro, a human born on (a habitable) Venus, a child of colonists. But interestingly enough, he's a man with little understanding of humor (due to the culture in which he was raised) and one of the earth born crewmen takes joy in teasing him. Hmm, now is it my imagination, or does that remind me of someone else?
Anyway, it seems Astro was human.