It wasn't Grace Slick. It was Signe Toly. She was Jefferson Airplanes first female singer. She was on the first album.
She was a friend of my wife's quite a few years ago.
Lots of people forget her ... kinda sad. She's no longer with us.
She was pretty darn good.
I actually liked her better than Grace in that band ... but that's just opinion.
Anyway, she was with them from around 64 or 65 I believe. She stayed with them until late 66. Quite a wonderful performer.
Not sure if the O.P. was looking for all female bands or bands with female members. Regardless, it seems to be evolving into early women Rock and Rollers so in that vein:
Julie Driscoll w/Brian Auger and Trinity.
Jazz also has a rarity of female performers- even today with 1000x times more people attempting to get a fraction of the gigs there were in the 50's and 60's there is still very few women.
The majority that come to mind in the heyday were either pianists or organists- Trudy Pitts, Shirley Scott, Mary Lou Williams, Toshiko Akiyoshi, Jutta Hipp, Alice Coltrane, Joann Brackeen and Carla Bley, Dorothy Ashby the original Jazz Harpist, Melba Liston the trombonist/arranger/conductor and barring singers- I don't think I can really name anyone else from the 1950-1970 era.
Rock bands have been around since Bill Haley - 1954.
I always assumed the first all female rock band was that Liverpool one, as they were contemporaries of The Beatles and played similar venues (1962/63)