Wow! So many recommendations. I've put them all together here for easy access for anybody who's as interested as I am! I've put the name of the author and then any particular information that was pointed out in the post that might be useful or relevant. ALSO I apologies if some names are listed twice, there were a lot of repeats!
109(ish) Female Fantasy Writers
Andre Norton
Ann Halam/Gwyneth Jones (YA)
Anne Bishop (‘Others’ series - incl. warning regarding references to sexual assault that aren’t always handled well)
Anne McCaffrey
Beth Bernobich (’The River of Souls’)
C. J. Cherryh (she writes SF and F)
C. L. Moore
Carol Berg
Caroline Stevermer
Carrie Vaughn or vaughan
Cat Rambo
Catherine M. Valente
DC Fontana (TV writer but also a worthy author to look up)
Diana Wynne Jones (‘The Merlin Conspiracy’, ‘Dark Lord of Derkholm’ (incl. male protagonist), ‘Year of the Gryphon’)
Elizabeth A. Lynn (‘Dragon's Winter’)
Elizabeth Bear (‘Range of Ghosts’ set in a world inspired by Asian cultures, particularly Mongolian)
Elizabeth Haydon (’Symphony of Ages’)
Elizabeth Moon
Ellen Kushner (‘Swordspoint’ (incl. male protagonist) and Privilege of Sword)
Emma Newman
Frances Hardinge (YA, Face Like Glass)
G. Willow Wilson (‘Alif the Unseen’)
Gail Carriger
Heather Rose Jones (‘Daughter of Mystery’, ‘Mystic Marriage’, ‘Mother of Souls’
Jacqueline Carey
Jane Yolen
Jo Graham
Jo Walton (writes SF and F - ‘Among Others’ (Hugo inner) and Lifeload)
Juliet Marillier
K. A. (Katherine) Applegate
K. J. Charles (‘The Charm of Magpies’, incl. male protagonist and sexual content)
Kameron Hurley
Kara Dalkey (‘Goa’, ‘Bijapur’, ‘Bhagavati’)
Kate Elliot
Kate Griffin (urban fantasy)
Katherine Addison/Sarah Monette
Katherine Kurtz
Kelly Link (“is weird AF”)
KJ Bishop
Kristen Britain (‘Green Rider’ series has female MC)
Kristin Cashore (Graceling)
Laini Taylor (YA fantasy)
Laura Anne Gilman
Lauren Beukes (from South Africa)
Leigh Bardugo (YA - ‘Six of Crows/The Crooked Kingdom’)
Leigh Brackett
Lindsay Buroker
Lois McMaster Bujold (‘Paladin of Souls’ and ‘Penric’s Demon’ - also a Hugo winner, incl. male protagonist)
Lois McMasters Bujold (both SF and F)
Lynn Fleweling (’Nightrunners’ series)
Madeleine L'Engle
Marie Brennan
Marion Zimmer Bradley
Martha Wells (‘Raksura’ series, first book being ’The Cloud Roads’)
Mary Robinette Kowal
Mercedes Lackey
Michelle West/Michelle Sagara (‘Hunter Lord’ duology)
N. K. Jemisin (’The Fifth Season’ - also a Hugo winner)
Nancy Springer
Naomi Novik (‘Uprooted’)
Nina Kiriki Hoffman
Nnedi Okorafor (MG fantasy, epic fantasy, SF + more)
Octavia Butler (‘Kindred’)
Patricia Briggs (urban fantasy)
Patricia C. Wrede
Patricia McKilip
Rachel Neumeier
Rainbow Rowell (Carry On and its contemporary sister, Fangirl, on loving fantasy and writing fiction about it)
Robin Hobb (The Farseer universe)
Robin McKinley
Sabaa Tahir (YA fantasy)
Sally Gardner (YA)
Sarah J. Maas
Sarah Rees Brennan (‘Wings in the Morning’ (novella-ish short story)
Seanan McGuire
Sharon Shinn
Sherri Tepper
Sherwood Smith
Stina Liecht
Tamora Pierce (YA high fantasy)
Tanith Lee
Tanya Huff
Traci Harding
Trudi Canavan
Ursula K. LeGuin (SF + F)
Ursula Le Guin
Quartzen on Twitter has Madde some moments full of female Space Opera writers:
1-100
https://twitter.com/i/moments/887032286432157696
101-200
https://twitter.com/i/moments/887025035399049217
[EDIT] - Edited to alphabetise.