Just came across Oksana Salii:
"We can do it!"
Perhaps a little borderline regarding"muscle", but Momo Tomomoto is a professional cosplayer: https://www.instagram.com/tmmt_cosplay/
And before anyone thinks "Lara Croft"...that's Rebecca "Revy" Lee from "Black Lagoon" XD
Svetlana Shesterikova had a habit of dressing as creepy clowns even before bulking up:
Apparently, she liked her Harley Quinn costume so much she even had a photoshoot:
Jeanie Welker as "Rosie the Riveter"
Some other Rosie cosplays: