I'm curious as to when the term "redshirt" is first known to have been used. Just in case anyone needs the background, from Wikipedia:
A "redshirt" is a stock character in fiction who dies soon after being introduced. The term originates from the original Star Trek (NBC, 1966–69) television series in which the red-shirted security personnel frequently die during episodes. Redshirt deaths are often used to dramatize the potential peril that the main characters face.
I'm wondering how early this trope was recognized and given its name. Did "redshirt" exist during the original series' run? Did it originate in online communities? Somewhere in between?