I also forgot Stephanie Powers as agent April Dancer in The Girl From U.N.C.L.E.
What I've read, though, is that she wasn't really allowed to be a strong heroine, that the network or the producers insisted that her male co-star do all the action stuff because it was unseemly for a woman. Which I can believe, since The Man from UNCLE
is often quite blatantly sexist to the point of misogyny (especially the episodes written by Peter Allan Fields, which is surprising, considering that he went on to write Kira and Dax so well in DS9).
I agree with the above mention of Batgirl as a great example of a strong woman in '60s TV. The network wouldn't let her throw a punch, but other than that, she was smart, fearless, capable, and resourceful, able to achieve everything Batman and Robin did without the resources of a multimillionaire as a crutch.
There's also Agent 99 from Get Smart
; she was the smartest, most competent secret agent on the show, albeit still very feminine.