At the moment, I have a crush on D’Arcy Wretzky from the Smashing Pumpkins, in the mid 90s.
Mid-1960’s Nana Mouskouri.
Also, early 2010’s Joumana Medlej. 
Too many to list, for longer than I care to remember.
So many people, usually.
And I don’t much like it. It can interfere with seeing them as people. At least, I’m afraid it does, and I try to prevent that.
Erin Gray - Buck Rogers in the 25th Century - 1979 - 1981
Christina Applegate - Married With Children - 1987 -1997
Juliette Lewis - Cape Fear - 1991
Deborah Norville - Circa 1990
I’m sure there are more if I thought long and hard.
ETA: Oooh. Heather Locklear - Anytime.
Amy Adams - 2007
Ching He Huang. i have a thing for cooks.
Elvis in the 50’s. He was so, so hot.
Richard Chamberlain in The Thornbirds. One of my first crushes- very painful 8th grade unrequited love for me. He was sexy.
Barack Obama. Regardless of your opinion of him as POTUS, you have to admit that he is charming and sexy as hell. If you can’t admit it, then I will. Michelle is a lucky woman.
And many more.
Diana Rigg, 1965-68
Michelle’s pretty damned sexy in her own right.
Erin Gray. OMG, yes! A thousand times yes!
Tupac for oh like the last 17 years…wow that makes me feel old and lame, but I love him just as much as I did when I was 14
And Dr. House, for some reason (not Hugh Laurie although he’s extremely talented and cool and probably sexy if you’re into that type of dude)
T.I. also as long as he shuts the fuck up and just looks pretty
Sigourney Weaver, circa Ghostbusters. She’s still damned hot, mind you, but back then, she was off the scale.
Present-day Ke$ha, of course
Denise Richards, Cameron Diaz, & Brooke Burke of late 1990s/early 2000s
Daisy Fuentes (MTV VJ), mid 1990s
Leonardo DiCaprio in 1997
Jared Leto in 1994
Marlon Brando in 1953
Teri Garr, Young Frankenstein era.
That’s not true.
I was just watching The Assassination Bureau and I can confirm Diana Rigg was still hot in 1969.
Miss Piggy.
Jessica Rabbit.
My heart beats faster for foreign men:
Benedict Cumberbatch as Sherlock
Michael Fassbender
Jude Law
And I always have a love affair for Robert Downey Jr and Alan Rickman.
My biggest crush was Barbra Eden from when I was a kid.
Then, in the 90’s, I watched a bio of her on TV and fell in love with her again once I realized what a cool person she was. Not your typical celeb, that’s for sure.
Tiffany Amber Thiessen (or however she spells it), back when she was on whatever show that was in her teens. (Saved By The Bell?)
Courtney Thorne-Smith, back when she was on whatever show that was in her teens. (Melrose Place?)
Bridget Fonda, circa 1995.
Mrs. Kotter, circa 1977. Bralessness was, and remains, a huge turn-on during my pre-teen years.