(coexisting on another dimensional plane)
Captain Michael Burnham was a female Terran Imperial Starfleet officer who lived during the mid-23rd century. A figure of immense prestige, during her career she won the Valor, Master of Poisons, and 100 Kills medals. (DIS: "Despite Yourself")
After her parents' death, Burnham was raised as a daughter by Emperor Philippa Georgiou, who she addressed as "Mother". Georgiou was keen on giving the best in everything to her daughter, however, she became jealous of Gabriel Lorca, when Burnham developed an interest in him as a father figure, and later as a love interest. (DIS: "Vaulting Ambition")
While in command of the ISS Shenzhou, Burnham was ordered to hunt down Lorca, who was attempting a coup against the emperor. Her shuttlecraft was destroyed during this operation, leaving her presumed dead and Lorca on the run afterwards. However, in reality, Burnham had turned on the Emperor and sided with Lorca, for which Georgiou issued a death penalty on her. (DIS: "Despite Yourself", "Vaulting Ambition")
The Michael Burnham of the prime universe posed as her, telling others in the Empire that she had faked her death in order to hunt down Lorca. With her apparent Gabriel Lorca posing as the Imperial Starfleet Lorca, she went to the ISS Shenzhou and assumed command from Danby Connor as part of a ruse to obtain intelligence that could help return the crew of the USS Discovery to their own reality. She subsequently killed Connor in self-defense when he attempted to assassinate her. (DIS: "Despite Yourself")
According to StarTrek.com, Burnham's shuttle was lost in the Cawdor system.
In the Star Trek: Discovery comic miniseries, Succession it was revealed that Burnham pretended ally with Lorca, in order to stop his plans. However, she could not reveal her plans to Georgiou. Burnham then hid herself on Risa and waited for her moment to strike. She eventually took the mantle of Empress from Georgiou's cousin Alexander (β). However, Burnham was killed by Airiam (β) who then succeeded her as Empress.