Ensign D'Vana Tendi (Noel Wells), whose enthusiastic effervescence contrasts the crusty and crude feline physician.
Due to the budgetary limitations of Starfleet Officer was also seen in live-action in Star Trek IV: The Voyage Home.
Dr. T'Ana isn't one of the main characters in Star Trek: Lower Decks since the animated comedy focuses on the junior officers like Ensign Beckett Mariner (Tawny Newsome), but she is a stand-out who gets memorable lines in every episode. T'Ana is gruff and lacking in patience or bedside manner, but the cat doctor does have a hidden softer side, and she had a romantic interest in the Cerritos' Bajoran Chief of Security, Lt. Shax (Fred Tatasciore), who once kissed her on the bridge. Unfortunately, her hopes to start a relationship with Shax were dashed in Star Trek: Lower Decks' season 1 finale when the Bajoran sacrificed his life to save his ship from the Pakleds. Dr. T'Ana was front and center at Shax's funeral, and she remains in charge of the Cerritos' sickbay and Ensign Tendi's superior officer.
As an animated series, Star Trek: Lower Decks makes it much easier for more elaborate humanoid alien beings to be prominent characters and Dr. T'Ana opens the door for other Caitians to appear in the franchise. Whether or not TAS is canon seems to change depending on the needs of the franchise, but regardless, M'Ress served on the Enterprise back in the 23rd century, over a hundred years before the setting of Lower Decks. But the Caitian race seems to be alive and well in the United Federation of Planets and there have been Caitians serving in Starfleet throughout the eras.
However, Captain Will Riker (Jonathan Frakes) mentioned to iral Jean-Luc Picard (Patrick Stewart) that the planet Nepenthe, where the Troi-Rikers made their home, was occasionally plagued by Kzinti raiders. Though the Kzinti weren't seen, Picard established that they canonically exist, and that means the Caitians - and in effect, Star Trek: Lower Decks - is also canon, since some fans harbor doubts whether animated Star Trek shows 'count' as the live-action series do.
The links between the Caitians and the Kzinti are even more fascinating as the two cat races actually share a common ancestry. They are cousin races who originated from the same planet before the more aggressive Kzinti splintered off eons ago to create a more warlike culture. In effect, this makes the Caitians and the Kzinti the feline equivalent of the Vulcans and the Romulans, who shared a common origin before the Romulans left millennia ago to carve out their own empire. It's possible, through Dr. T'Ana, Star Trek: Discovery's 32nd century, just as the Vulcans and Romulans were unified on the planet Ni'Var thanks to the work of Ambassador Spock (Leonard Nimoy).