Yup, me too! I didn’t believe my mom for years when she told me Neil Sedaka was a guy. Still not entirely convinced…
The first time I heard Simply Red’s “Holding Back the Years” I didn’t expect the lead singer to be/look like Mick Hucknall. I was 14 and loved that song.
LH
Former Morning Edition host Bob Edwards.
Robert Lee, the narrator of Mythbusters doesn’t look at all like I expected. Rankopedia - Find the best online casinos
Leslie West, of Mountain. Somebody told me he weighed about 300 lbs,and I had, for some unfathomable reason, a picture of Hulk Hogan in mind. Not even close.
Madeleine Peyroux does not sound like a cute white chick.
That’s how it worked for me, too. I got an LP of his from the library with his picture on it, and when I first listened to it, I wondered if the record and the cover sleeve had got mixed up. Now he’s probably my favourite of the old blues hounds.
I pictured Bela Fleck, with his name and unique mix of genres (a cross between bluegrass and jazz), to be an older, seasoned musician, maybe black or European, or both, but definitely a distinct looking character. I wasn’t sure what instrument he played, and when I first saw a video of his band performing, I wondered who the average white guy who could pass as an insurance salesman was on banjo.
He’s a lot thinner now.
Lighter too, in part due to losing a leg to diabetes.
Still rockin’, though.
Damn he’s hot. I don’t know how I missed that all these years.
Who I imagined was singing the first time I heard her wouldn’t rule out cute or white but I really expected someone larger, less angular, and quite a bit older.
Bad toupe type.
Roy Orbison was quite a mismatch.
Holy crap, he looks horrible in that Wikipedia picture. He was a pretty okay looking fellow back in the 1980s, if a bit pasty white.
A couple more radio voices that surprised me when I saw their pictures:
BBC’s Neil Nunes. He sounds like a guy I know, with an British accent that has an unusual twinge, so I always pictured him as a tall, rotund, bald white guy with a big moustache… with a monocle to reflect his vague Britishness. Dude’s a nice-looking young-ish Jamaican chap. Looking online, I see bitching about his Jamaican accent (via this article on annoying radio voices), but I definitely don’t hear it, and I also like his voice and overpronunciation. (I do like a quote from that linked article: “His voice sounds like it is coming out of the funnel of a container ship.”)
NPR’s Diane Rehm. I figured she was old, but her spasmodic dysphonia made me think she was doddering, frail, and covered with cobwebs. She’s older, yes, but is the very representative of a “handsome woman.”
And one voice that I knew but still shocked me… Meshell Ndegeocello. I knew who she was, liked her singing and deep voice, but for ages I thought the main vocals in Basement Jaxx’s Right Here’s the Spot was some male pop singer. Then I bothered looking at the liner notes and was all :smack:. In my defense, everyone I’ve played the song for has thought it was a guy (usually Justin Timberlake).
Wow! I had something much closer to Tracy Chapman pictured.
Huh? Except for sounding almost as much like Billie Holiday as David Sedaris she sounds exactly like a SEXY, cute white chick.
If her name was any whiter it would be translucent.
The first time I heard her, I thought it was Ella. I think the song was Leonard Cohen’s Dance Me To The End Of Love…
On listening more I have to agree with your Billie Holiday call but not your white chick 
Jay Kay of Jamiroquai did not look like I imagined
Dobie Gray(RIP) was a black guy but I used to imagine an older, white Willie Nelson type guy.
Sophie B.Hawkins, with her song “Damn I Wish I Was Your Lover”, I thought she would be a hottie but she was pretty average.
However as a kid if I imagined a singer was an attractive woman, chances were most likely they were. Examples include Lady Miss Kier of Deee-lite, Merril Bainbridge(had a hit called “Mouth”), and Amy Grant.
But number one of all time has to be for me Ali Campbell of UB40.
The lead singer of Romeo Void (“Never Say Never”) also shocked me.
On the flip side the singer of Midnight Oil turned out to be the way I expected him to look, which is the only time that has happened.
Madonna. First time I saw her I found her disappointingly plain, especially during the “Material Girl” MV where she was copying Marilyn. But she grew on me.
Patti Smyth. She could have been younger and more hyper.
Lady Gaga - I still don’t know how she really looks. 
Rick Astley! I was shocked when the first time I saw what I thought was a humungous black dude was actually a kind of skinny Irish-looking nebbish.
No offense intended, since I like his music, but I once found myself standing next to Jose Feliciano at JFK as he was making calls on his mobile. Trust me when I say he’s nowhere near as impressive when he’s not wearing his dark glasses. 