(coexisting on another dimensional plane)
Commander Ellen Landry was a female Terran Starfleet officer who lived during the mid-23rd century. She was one of the most trusted followers of Gabriel Lorca, assisting him in his coup against Emperor Philippa Georgiou.
After Lorca's coup was defeated and he was presumed dead, Landry was captured and held in an agony booth on board the ISS Charon. She was rescued by Lorca when he returned from the prime universe, and she helped him in overtaking the Charon, facing Georgiou and her loyal force. They made it to the throne room and Landry confirmed the crew was either dead or switched sides. Then, she fought Michael Burnham when the USS Discovery attacked and jolted the ship and was knocked out. When she awoke, she realized the others were gone, just before realizing the Discovery was attacking the ship's core. She was killed as the Charon was destroyed. (DIS: "What's Past Is Prologue")