Angelique Pettyjohn from ST:TOS - The Gamesters of Triskelion. Apparently she did some porn too. Unfortunately, she passed away in 1992. 
We’re up to page 2, and post #80, and no love for
Deborah Foreman - especially her roles in Real Genius, and My Chauffer. (Yeah, I like grade-A Wisconsin in my 80’s movies.)
Also from Real Genius: Michelle Meyrink
(And wasn’t that a movie for eyecandy, both male and female?)
She’s not obscure, now, but I really started to dig this one actress I first saw in one of the Robocop sequels. (The best part of Robocop III, IIRC) I even made the point of staying to watch the credits to catch her name: Jill Hennessey.
Oh, BTW, I refuse to humiliate myself by recounting various animated crushes I may have had. 
I was gonna mention Horschack, but I was . . . ashamed.
Before the Dope timed me out and I couldn’t edit (I know, that could never happen here), I was gonna mention the fact that Vinnie was smoking hot but way outta my league. Horschack seemed, well, kinda like me.
and
Gangster Octopus, did you see Greta in White Mischief. She almost turned *me * straight, she was that beautiful and luscious, she was.
Add another vote for both:
Randolph Mantooth from Emergency
Paul Michael Glaser from Starkey and Hutch
Also Jason David Frank as Tommy Oliver, Best Power Ranger Ever!
One of my earliest was Lara Parker who played the witch Angelique on “Dark Shadows”.
More recently, Madchen Amick from “Twin Peaks” and more recently the horrible “Joey” Friends spin-off that I actually watched just for her!
Rhoda the Robot was the statuesque Julie Newmar on “My Living Doll”, the show that forever more made me believe that the sexiest thing a woman could wear is a simple lace full slip.
I still think that Elizabeth Montgomery from “Bewitched” is one of the prettiest women to ever grace a television screen.
I have no such pride, so I will mention my first crush ever, which was on Brian Bedford’s voice as the foxy lead in Disney’s Robin Hood. I listened to that record a million times. And I still have it, by the way. 
Even more obscure: Dave Debusschere, #22 on the NY Knicks. Hey, I watched the Knicks on TV, that’s gotta count! Helped 'em win two championships, later became head of the ABA, and was the youngest coach in NBA history. Also one of the few sports figures to play pro basketball and baseball. (But as a 7-year-old I just thought he was cute.)
Karen Valentine in Room 222. I couldn’t wait to get to High School and have a teacher like her.
Anybody remember the short-lived American version of “That Was The Week That Was”? Remember the singer, Nancy Ames?
I remember her. She floated my teenage boat every week.
Just as embarrassing: I had a big crush on Casper the Friendly Ghost.
And Sidney Poitier from To Sir, With Love.
I had a huge crush on Charmian Carr who played “Leisl” in the Sound of Music movie. (Sh’es the one who sang 16 going on 17).
And Tatum O’Neal from the original Bad News Bears.
ETA: And Marianne NOT Ginger from Giligan’s Island.
My sister’s picks: Jo from Facts of Life, Sabrina from Charlie’s Angels and… A Martinez from Santa barbara and LA Law.
Sandy Farina, who played Strawberry Fields in the film Sergeant Pepper’s Lonely Hearts Club Band. Lousy film, but an oh-so-pretty young lady to this then-teen.
Jessica Harper, who played Phoenix in Phantom of the Paradise. When she sang the song “Old Souls” in the film, I melted. Still do, actually.
Not-That-Obscure
Markie Post from Night Court, Fall Guy and some Love Boat guest appearances.
Bebe Neuwirth from Cheers
Eve Plumb from The Brady Bunch (the last season or two, not the early shows)
A-Little-More-Obscure
Randi Oakes from CHiPs
Hanna Schygulla from the movie Delta Force
Oh, and non-crush-related:
It’s Your Move was an awesome little show. It had a touch of that amoral edginess that would later become mainstream in shows like Seinfeld, but was fairly “dangerous” for 1985.
I thought she was going to be #1 and here she is finally coming in at #77, I cannot believe it. And still no Hayley Mills?
Oh yeah. Girl crush on her!
I really think you have to vote that as the weirdest crush in history. (Did you know his real name was Ross Bagdasarian? Aren’t you glad you didn’t marry him now?) I can just see Alvin as the best man.
Elisabeth Shue in Adventures in Babysitting. First time I sported wood.