Tia from Escape to Witch Mountain, I suppose. I was maybe seven, she was – what – nine?
Emma Peel from The Avengers (the real Avengers, not those comic book characters!)
I don’t remember, but I’m gonna go with Julie Newmar as Catwoman.
Willy Wonka (the Gene Wilder version).
Nothing has changed. 
Crystal Mace from Space Angel.
Batman
Marina, Aqua Marina! Rumors are that she was based on Brigitte Bardot.
I can well understand that; access to unlimited amounts of candy. Plus one can get up to all sorts of erotic games involving that river of chocolate.
Mr. Spock.
Billie Jo on Petticoat Junction (as played by Meridith McRae),
Leslie Ann Warren as Cinderella. I must have been four. I always liked older women.
Julie on Electric Company. She was one of the Short Circus kids. Also Penny from Lost in Space.
I was torn between Valerie and Bonnie Franklin (the Mom).
Penny Robinson.
Kathy or Patty from the Patty Duke show.
Barbara Eden on I Dream Of Jeannie
When I was a kid one of the books I read was about a couple of boys visiting a dude ranch, and there were girls there. I no longer remember the fictional girls’ names but there was something about that whole scene that made me really want to be there!
I think it’s generally acknowledged among all boys that Emma Peel (Diana Rigg) was hot!
Also Carol Demas from “The Magic Garden”
Same here, Lynda Carter as Wonder Woman.
Robin, of Batman and Robin fame. I was eight, so long before puberty. First in comic book form, then on the TV show played by Burt Ward.