Tasha Yar's younger sister, a member of a Turkana IV faction who used the Enterprise-D crew to further her side's war.
Ishara Yar grew up on the failed colony of Turkana IV, where she stayed behind when her older sister Tasha escaped the planet's gang warfare. By the time the Enterprise-D arrived to rescue two stranded Federation crewmen in Legacy, she had become a member of the Coalition, one of the factions fighting for control of the colony.
She offered to help the away team and won Data's trust, partly because of his friendship with her late sister. Her real aim was to disable the rival Alliance's defences. Data uncovered the plan and stunned her before she could act, and she was returned to Turkana IV, leaving Data to reflect on how different the two sisters had been.