For many men of a certain age, and more than a few women, Yvonne Craig's Batgirl represented their first childhood crush. Confidant, sassy and just a little flirty, her heroine was a chaste counterbalance to the overtly sexual Catwoman, whether played by Julie Newmar or Eartha Kitt (there's probably a master's thesis in that). She was the purple-suited equivalent of your best friend's older sister, or your next-door neighbor -- the smart-and-pretty girl whom you thought you might have a chance with.
Batgirl was also wildly popular, even as Batman's ratings flagged in its second season, as these 1967 photos from The Merv Griffin Show demonstrate. While the images have cropped up online before, it was difficult to pass them by when they appeared again overnight on Retronaut; I even poked around to find a couple of more shots of Craig backstage. It's difficult to imagine an actor like Christian Bale, Scarlett Johansson or Chris Hemsworth to appear in superhero costume on The Late Show With David Letterman or Conan, but there Craig is, looking like she's having a blast.
As a bonus, I've also thrown in a photo Leonard Nimoy tweeted earlier this week of him drumming with Adam West, presumably in the late 1960s.