The original Star Trek had some revealing William Theiss costumes for the ladies that were’t done that way for a looong time!
That's an understatement.
Sherry Jackson in her "uniform" was hot.
And Theiss was gay.
A real talent as a designer.
But I think the sexiest costume was that Erin Grey disco pants look of the late 70s.
BTW, for all of the hating on Space:1999, they had one of the scariest episodes I've ever seen on TV.
Dragon's Domain.
This one eyed, hypnotizing monster that vacuumed up astronauts and spit out their charred corpses.
Scared the crap out of me when I was 9.
I had no objections. :)