Gabi Braun

Age: 12,
15 (at the end)
Relative: Reiner Braun (cousin)

Gabi Braun is an Eldian in the Marleyan Military, being trained in the Warrior Unit as a Warrior Candidate, to potentially one day gain and fight with one of the nine titan powers.

She is a valued candidate to inherit the Armored Titan power.
(Source: Attack on Titan Wiki)