Most Helpful Guy
God... dammit. I had this long answer typed out and I accidentally exited the page. >.< Okay. "Yaaaay this is my topic!" Except you also included rock, so I'll try to add some female rockstars instead of *ALL METAL* which is my impulse. And you know I can't just post one. There are too many.
1. Otep Shamaya. She sings, she screams, she raps. (She's hot as fuck.) She voice acts. She writes. She has it all. She is my demoness.
2. Angela Gassow --her scream is the sickest of all. Most metal singers sound entirely different live than on an album version. Devildriver completely disappointed me, in particular. But Angela's voice is seriously that raw on the album *and* live. https://www.youtube.com/watch?v=mYtMSZQ7q9A
3. Emily Haines from Metric, I guess. She can play the piano. Live, Haines sings and plays two synthesizers, and sometimes plays the electric guitar. Pretty sure almost everyone has heard Gold Guns Girls.
4. Sarah Barthel from Phantogram. Her voice is magnificent.
5. Amy Lee from Evanescence, because, obviously.
Don't ask me to find a funny female comedian though. I don't think one exists.
I think these might ultimately just be my favorite female artists instead of who I think is the most talented overall... But hey. They are all really talented.
Most Helpful Girl
Oh man, so many...
Mary Timony from Helium
Shirley Manson -- Garbage
Distillers -- can't remember the singer's name...
My 13-year-old son has NO qualms about singing the (women's) vocals for this song when he plays Rock Band with his football friends, which I think is pretty fucking cool <3
You might know it from Gran Turismo:
Also, Karen O from Yeah Yeah Yeahs... Courtney Love... Ann Wilson from Heart... and those are just the ones that come to mind in the first 30 seconds.