This promo shot shows U.S. actress Stefanie Powers and was made for her The Man from U.N.C.L.E. spin-off show The Girl from U.N.C.L.E., on which she starred as secret agent April Dancer. She would later go on to become widely known while starring in the 1979-84 sleuthing weekly Hart to Hart with Robert Wagner. The photo is from 1966. You can see another one here.
You like my gun? I made a few modifications. It doesn't fire anymore, but it scares the absolute crap out of people.