Naquasia LeGrand was frying chicken, sweeping floors and serving customers for $7.25 an hour when she was recruited by union organizers to join a campaign for higher pay.

In the 15 months since, the 22-year-old KFC employee from Brooklyn has become one of the most visible faces of a movement that has staged strikes across the country demanding a $15-an-hour wage and union representation for fast-food workers.