The Walking Deadfans have been through a lot this year, but it looks like they might have another fan-favorite loss incoming. Series starSonequa Martin-Green, who plays Sasha on AMC’s hit zombie apocalypse series, has landed the lead role in CBS’Star Trek: Discovery. Martin-Green will be the first African-American woman to lead the cast of a Star Trek ensemble and perEW, she will play a lieutenant commander on the titular spaceship.

The report states that Martin-Green will continue to star onThe Walking Dead, but I’m taking that statement with a big “for now” since the sustainability of that arrangement is questionable in the long run.The Walking Deadfilms in Georgia whileDiscoverywill shoot in Toronto, Canada, and while a gap inTWD’s filming schedule may allow Martin-Green to remain on board the series for a time,Discoveryis a massive project for CBS and it’s hard to imagine the actress will be able to balance the filming schedules and promotion rounds for both for too. Plus,The Walking Deadkills everyone, and Sasha’s already been around longer than usual for a non-OG character.

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Martin-Green is the latest addition to the series, which is casting up at a fairly rapid rate.Michelle Yeohwas thefirst actor to board the seriesas the captain of another ship, the Shenzhou. Elsewhere, professional chameleon and exceptional prosthetics performerDoug Joneswill introduce a brand new alien species to the Star Trek universe as Lt. Saru the main Starfleet Science Officer.Anthony RappofRentfame will play the televisedStar Trekuniverse’sfirst gay character, Lt. Stamets, an “astromycologist,” fungus expert, and Starfleet Science Officer aboard the Starship Discovery.

Earlier this week,DiscoveryaddedChris Obi,Shazad LatifandMary Chieffoas atrio of Klingons– T’Kuvma (Obi), a leader seeking to unite the Klingon houses; Kol (Latif), a Klingon Commanding Officer and protege of T’Kuvma; and L’Rell (Chieffo), the Battle Deck Commander of a Klingon ship.

Star Trek Discoveryis scheduled to premiere on CBS All Access May 2017.