
Avengers: Doomsday has assembled quite an impressive cast, including several characters from the Black Panther side of the Marvel Cinematic Universe. Black Panther: Wakanda Forever was released as part of Phase 4 of the MCU and continued the story of the hidden nation of Wakanda after T'Challa's (Chadwick Boseman) tragic demise, focusing on setting up new characters to carry the Black Panther mantle. Several of these Black Panther characters' stories will continue in the next major superhero team-up movie in the MCU.
Avengers: Doomsday recently shifted to a new release date and is being directed by MCU veterans Anthony and Joe Russo. Other Marvel stars reprising their roles include Chris Hemsworth, Pedro Pascal, Florence Pugh, Paul Rudd, and Sebastian Stan.
Avengers 5 Will Return to the MCU's Wakandan Roots With These Black Panther Characters
Shuri

After the mantle was officially passed to Shuri (Letitia Wright) in Black Panther: Wakanda Forever, the character will make her Avengers debut as the Black Panther in Doomsday. Wright was previously spotted training for her upcoming Avengers role, but has since confirmed that she has wrapped filming on Doomsday.
With Tony Stark out of the picture, Shuri's immense intelligence and knowledge of technology will be an asset to the team in whatever Multiversal peril they find themselves in, particularly if she teams up with other brilliant minds, like Reed Richards.
Namor

Tenoch Huerta's underwater ruler, Namor, served as the antagonist in Black Panther: Wakanda Forever, but ultimately, he only wanted what was best for his secret nation of Talokan. Eventually, the Talokanil and Wakandans formed a truce, which may be called upon in Avengers: Doomsday.
Namor's role in the film may also serve another purpose, as the Submariner is one of the few confirmed mutants in the MCU right now, which could prime him to connect to the returning X-Men characters in Avengers 5.
Huerta recently opened up about how Namor will play into the film, admitting on La Resolana Con El Capi (via Deadline) that it will be "a smaller role" given the sheer scale of the cast:
“The dynamic has been different... There are twenty-something characters involved in the story, which means we are each going to have smaller roles because there needs to be space for all the characters and all the universes. This makes it a much more simpler role, in terms of time and energy of making a film like this.”
M'Baku

Leader of the Jabari tribe and now King of Wakanda, M'Baka (Winston Duke) stepped into the monarch role after the passing of T'Challa and Queen Ramonda, and when Shuri decided to take her new Black Panther suit and travel the world. While M'Baku has often opposed the Black Panther, he's ultimately proven himself to be a loyal friend and a fierce warrior.
Duke has already been spotted on the Avengers: Doomsday set and will no doubt be important to the story as the new leader of Wakanda, particularly with Doctor Doom (Robert Downey Jr.) as one of the main antagonists of the latest Avengers film. In the comics, Doom shows an interest in Wakanda because of its vibranium, which could signal another trouble for the hidden nation.
Namora

Namor's friend and confidante, Namora (Mabel Cadena), was against the Wakandan truce in Black Panther: Wakanda Forever, which led her to butt heads with Talokan's leader. But with Talokan seemingly a part of the plan for Avengers: Doomsday, it makes sense that Namor's closest advisor will be a part of the action as well.
Cadena was not included in the initial cast list for Avengers: Doomsday. However, the actress was spotted with several MCU cast members in Bahrain during Avengers: Doomsday filming, suggesting she will return as Namora in the film.
Attuma

Another of Namor's trusted warriors, Attuma (Alex Livinalli), was a formidable opponent in the Wakanda/Talokan battle. Like Cadena, Livanalli was spotted in a cast photo during Avengers 5 filming, which more or less confirms that the Black Panther: Wakanda Forever star will reprise his role.
If Doctor Doom's master plan involves vibranium that puts a target on Talokan as much as it does Wakanda, meaning the two nations may need all their warriors to fight the impending doom.
Bonus: Bucky Barnes

After Captain America: Civil War, Bucky (Sebastian Stan) hid in Wakanda as he recovered from his HYDRA brainwashing and became known in the nation as the White Wolf. Bucky is a close ally of Shuri's, with the latter responsible for creating his upgraded Vibranium arm.
With the Winter Soldier now a member of the New Avengers, this could test Bucky and Shuri's friendship in Avengers: Doomsday, depending on which Avengers team's side the Black Panther falls.