Why Namor Says Imperius Rex And What It Means
Black Panther: Wakanda Forever introduced Namor the Sub-Mariner to the MCU and the iconic catchphrase "Imperius Rex" from the comics.

Black Panther: Wakanda Forever introduces the Sub-Mariner Namor to the MCU, including his classic catchphrase "Imperius Rex!" Namor, played by Tenoch Huerta, makes his debut as the ruler of the undersea kingdom of Talokan and is considered a K'uk'ulkan god avatar. After Wakanda refused to form an alliance to conquer the world, Namor led Talokan to war against Wakanda. This culminates in a final reckoning between Namor and the MCU's new Black Panther, Shuri.
While their armies battle in the ocean, Shuri and Namor face off on land for the final showdown of the superpower ruler. Responding to Shuri's "Wakanda Forever" battle cry, Namor responded in his own way: "Imprys Rex!" With Wakanda Forever coming to Disney+, it again brings up what that line means The problem. When he waits until the third act of the movie to utter the line, it's a classic line from King Talocan in the comics. Roughly translated from Latin, it means "King of the Empire". As such, the line is a dynamic reference to the antihero's comic origins, while also making him an epic throwback to classic Wakandan phrases in the MCU.
How Marvel Comics Explained Namor's Imperius Rex Battlecry
Although there is no literal translation, Namor's The catchphrase "Imperius Rex," which sounds scary while fitting his name, was originally conceived by Marvel Comics writer Bill Everett, who simply reversed the spelling of "Roman." That being said, there is an example in Marvel Comics, in 2018's Thor #1, when they got into a fight, Thor finally asked Namor what the catchphrase meant. Namor offers a less serious answer, saying "Which means I'm going to feed your sorry Asgardian hide to the biggest shark I can find!" though never really accurately explaining Namor's iconic battle cry What it really means, but it sure sounds cool (and that's the point).
Why It's Good The MCU Included Namor's Imperius Rex Catchphrase

Keeping in mind the original comics, MCU Namor's catchphrase "Imperius Rex" also has no explanation, which is fitting. In fact, Namor's "Reaper of Souls" battle cry has a lot to do with the submarines on screen, given that Namor ruled over Mesoamerican-inspired underwater Talocan, rather than Atlantis and its Greco-Roman origins. It doesn't make much sense to say. In fact, it's just an interesting reference meant to honor the character's comic book roots, proving that even though his Talocan kingdom is different from the MCU, it's a good representation of the character.
Although "Imperius Rex" is quite An epic verbal Easter egg, notable that Namor and his people also have "Rise Talokan!" as an impressive battle cry, which is spoken in their own language. Regardless, it'll be interesting to see if Namor's iconic series gets a more direct origin and translation as the future of the MCU Sub-Mariner emerges. For now, it's certainly a nice touch for his final battle in Black Panther: Wakanda Forever.
Why Marvel Should Never Properly Explain Imperius Rex

While the meaning of "Imperius Rex" remains a mystery, it really doesn't need to be solved. While Captain America's "Avengers" and Black Panther's "Wakanda Forever" have obvious meanings, there are other comic book catchphrases that don't need meaning. When Doctor Strange says "Hoggoth's ancient hosts," no one really needs to know what those hosts are. It's perfect for Strange. When Namor yells "Bossy Rex," no one really needs to know what that means. It just screams out Namor's arrogance.
There has been confusion over the meaning of "The Domineering Rex" dating back to Namor's appearance in Marvel Comics in the 1960s. When Stan Lee started using it all the time, readers asked What that means on the letters page, Lee actually responds at one point is that no one knows why Namor is yelling like that - not even himself. In fact, the catchphrase sounds majestic, which is really the only meaning it needs to mean, whether in the comics or in a movie like Black Panther: Wakanda Forever.