I keep thinking I see headlines about "All-Girl Lord of the Rings," and thinking, "Yeah, I'd watch that."— Charlie Jane Anders (@charliejane) September 2, 2017
I'd watch that, too. Much as I love the LOTR films, they're about as monolithically male as any movie that doesn't involve a submarine can be. Considering all the excellent female actors who were sidelined by the gender skew of the source material, I started to wonder who I'd want to see in those roles if the situation were flipped. Here's my list. I tried to avoid choosing actors who are primarily known for SF&F work, but I'll admit that my choices lean toward people from movies & TV shows that I love.
Gandalf: Helen Mirren
Frodo: Tina Fey
Sam: Amy Poehler
Merry: Mindy Kaling
Pippin: Ellie Kemper
Aragorn: Charlize Theron
Legolas: Rosie Perez
Gimli: Kathy Bates
Boromir: Michelle Yeoh
Elrond: Audra McDonald
Eomer: Robin Weigert
Theoden: S. Epatha Merkerson
Wormtongue: Melissa Leo
Faramir: Sonja Sohn
Denethor: Diana Rigg
Bilbo: Frances McDormand
Saruman: CCH Pounder
Gollum: Kate McKinnon
Male versions of Galadriel, Eowyn, and Arwen are left as an exercise for the reader.