who is the mother of martian's daughter in the agency

Martian’s daughter is Poppy, and the most supported answer is that her mother is not explicitly named in the available coverage; the show appears to treat Martian and Poppy’s mother as separated or off-screen.

What the show indicates

• Martian is shown with his daughter Poppy in London.

• Commentary on the series says Martian and the mother of his daughter are separated.

• Public recaps and cast guides do not identify a specific mother by name in the material surfaced here.

Why the confusion happens

• The series also centers on Sami Zahir, Martian’s romantic interest and affair, which can make viewers assume she is Poppy’s mother.

• But the coverage distinguishes Sami from Poppy’s mother rather than identifying them as the same person.

Plain answer

At this point, the safest answer is: the mother of Martian’s daughter has not been clearly identified in the sourced material, and she does not appear to be Sami Zahir.

TL;DR: Poppy is Martian’s daughter, but her mother is not publicly confirmed in the sources reviewed.