While we thought Marvel Studios had created an original superhero for today's Moon Knight finale, it turns out they are from the comic books, and you can find details from the actor and producer here.
One of the most important characters in Moon Knight is the wife of Marc Spector, Layla El-Faouly, who becomes his reason why he holds on to Khonshu with a threat on her being his replacement as the Egyptian god of the moon’s avatar. As seen in Episode 6, the finale, Layla accepts to be a temporary one for Taweret and she unveils her cool costume with gold wings. Is she the Scarlet Scarab now?