Mera (DC Extended Universe)

Y'Mera Xebella Challa (more commonly referred to as Mera) is the deuteragonist of the 2018 film, Aquaman. She is the daughter of King Nereus and a Xebellian princess raised by Atlanna as well as an ally of Aquaman, prince and later king of Atlantis. She convinces Arthur Curry/Aquaman to go against Steppenwolf and he ends up joining the Justice League as a result. Later, she convinces Arthur to claim his heritage as king against Orm to protect both the remaining kingdoms of the Seven Seas and the surface world from the latter's wrath.