William H. Macy (maybe a little less these days, but I’d still do 'im).
I definitely see the appeal of Rob Corddry, but the short-lived Studio 60 on the Sunset Strip turned me into a bigger admirer of his brother, Nate. Though admitting so makes me feel like a dirty old lady.
I know there are others, I just can’t think of them at the moment…
At some point during Men of a Certain Age I suddenly found myself thinking, “Woah, is it just me or is Ray Romano looking kind of…hot?!?” (Extra weird since Scott Bakula was the reason I started watching.) It’s not an enduring hotness for me, though; he’s not on a list or anything.
There are many but the first one that I thought of is Carrie Preston. She plays Arlene on True Blood, she’s Sookie’s waitress co-worker.
Not a celebrity, but may I mention a woman whose voice is enough to make me stop what I am doing and listen to the Kaiser-Permanente commercials she does on radio? She has a low voice, very confidential-sounding, what W. C. Fields called a voice you could pour over waffles. Has anyone heard her?
Janeane Garofalo. She’s on my list, too. 
Merritt Wever
Rebecca Field
Alia Shawkat
Lauren Ambrose
Yeah, with women what you’ll mostly get is obscure, like Dichen Lachman (Dollhouse).
I go through phases. I had a bit of a sleb-crush on Catherine Keener for a while, and still find Victoria Coren lovely (although she’s recently married which takes some of the bloom off).
And of course Christina Hendricks bypasses all rational brain functions and goes straight to my brainstem leaving me glassy-eyed and muttering homina homina homina but I suspect she does that to most men.
I was always partial to Johnny Galecki, ever since he played David, Darlas’s boyfriend, on the show Roseanne. I don’t know if you could call him then, or now, a hottie. But I sure sit up straight whenever he plays a guest role in anything I’m watching.
It’s Russell Tovey for me (Being Human and Him & Her)…it’s the geeky guy next door plus his dog is the most adorable thing ever (and I normally don’t like smallish dogs)
I always thought she was pretty on True Blood, but she had a recurring cameo on The Good Wife (which she just won an Emmy for) and there were moments when that character was definitely kinda hot.
She is a celebrity: those commercials are voiced by Allison Janney, most notably of West Wing fame (she played CJ). A few years ago she co-starred in the very-short-lived *Mr. Sunshine *(with Matthew Perry), and she’ll be playing Anna Faris’s mother in the upcoming new show Mom.
Does your back hurt after watching episodes of The Big Bang Theory? 
Bill Maher, I love that guy so much that sometimes I can hardly stand it …
Margaret Cho
Does Illeana Douglas count as non-mainstream enough? I occasionally hear people complain about her looks, but oh my gosh, so different from run-of-the-mill blondes with surgically proportioned features. Those great moon eyes! That bladelike nose, that quirky smile! She’s mesmerizing.
For sure. I’ve always though Illeana is foxy—but never confessed that to anyone until now.
I’ve always liked her, too.
Apparently, I don’t have a “type,” because my odder celebrity crushes have included Clancy Brown (from his role in Buckaroo Banzai,) Roseanne-era John Goodman, and Craig Ferguson.
Laurie Berkner. Made watching Nick Jr with my little ones almost bearable.
What about Regina Spektor? She looks stunning to me, but I seldom see her come up in conversations. Does she count as unconventional for this thread?
I’m a HUGE Supernatural fan and Mark Sheppard (aka Crowley- ‘King of Hell’) is an interesting choice. I can see the attraction. But Dean (the most ridiculously handsome of them all) is the one who makes me weak in the knees… 