Mirror universe
Argo was a male Terran of the mirror universe and the younger brother of Philippa Georgiou.
In the early 23rd century Argo lived and worked at his parents' homestead on a planet in the Terran Empire when Philippa returned from a contest to determine the next emperor. He was particularly excited to see his sister again, informing his parents and being the first to run up and greet her with an embrace.
That evening, though, he and their parents were poisoned by Philippa as part of the final test to prove her worthiness as emperor. The soon-to-be Emperor Georgiou wept over her brother's body. (Star Trek: Section 31)
Argo was played by Nikita Kim.