Supergirl reimagining Nia this way is monumental given that she'll be network television's first transgender superhero and the character is actually being played by a transgender actress, a concept that certain studios don't seem to be able to understand that Hollywood needs way more of.
While Maines is relatively new to acting, she first entered the public spotlight as a teenager in 2013 when the Maine Supreme Court ruled that it was unlawful for her high school to deny her access to the girls' bathroom.
Nia is described as a "soulful young transgender woman with a fierce drive to protect others".
If the name Nia Nal sounds familiar, it's because she is the ancestor of Nura Nal, the comic book character you might know best as Dream Girl, a member of the Legion of Super-Heroes.
The cast and crew of Supergirlrevealed a new addition to the cast at their panel at SDCC.
"I haven't really wrapped my head around it", Maines told Variety. "It feels fitting to say with great power, comes great responsibility", adding, "I'm nervous because I want to do it right". Fans may know Maines from shows like Royal Pains and The Trans List. There will apparently be many parallels between her journey to self-discovery and destiny fulfillment with Supergirl herself - we'll just have to wait and see what those similarities will be.
Maines hopes the "Supergirl" casting is part of larger wave of the "right representation" of the trans community. "And what we see on television has a very dramatic effect on our society". She also did a guest stint on Royal Pains.
"I think that cis gender actors don't take roles out of malice, it's just a failure to realize the context of having cis gender people play trans gender characters".
"Having trans people play trans roles show that we are valid in our identities and we exist".
On Saturday, Supergirl also announced two other additions to the cast: new series regular April Parker Jones as Colonel Haley and David Ajala (Nightflyers, Falling Water), who will recur as the DC comics character Manchester Black.