As a kid I had a slight confused crush on Batgirl from the 60's Batman TV show. But not Barbara Gordon, just Batgirl. And when I was slightly older, Mindy from Mork & Mindy.
Edit: Also Jedi-era Carrie Fisher.
Additional edit/update: But those were just "dim pre-hormonal awareness" levels of a crush. If we're talkin' "I'm old enough to get how all this
blog works and I genuinely think about this person in a way that'd make me (and perhaps them) uncomfortable if I ever publicly admitted it," that'd probably have been Mia Sara as Sloan in "Ferris Beuller's Day Off."
And now I've said too much.