Bianca is an actress who portrays Sansa Stark in The Bloody Hand, a comedic reenactment of the prelude of the Westerosi War of the Five Kings, performed by Izembaro's theatre troupe in Braavos. She is jealous of Lady Crane, who portrays the much larger role of Cersei Lannister (Sansa only has two lines). As a result of this obvious jealousy, Arya suspects Bianca is the one who hired the Faceless Men to kill Lady Crane, but Jaqen refuses to indulge a girl's speculation. 
The next day, as the play finishes, Arya notices Bianca secretly mouthing Lady Crane's lines from backstage, confirming her suspicions. Though Arya poisons Lady Crane's rum, she stops her from drinking it and tells her to watch out for Bianca.
Days later, Lady Crane reveals to Arya that Bianca will have a hard time finding work as an actress considering what Lady Crane did to her face.
|Season Six appearances|
|The Red Woman||Home||Oathbreaker||Book of the Stranger||The Door|
|Blood of My Blood||The Broken Man||No One||Battle of the Bastards||The Winds of Winter|
In the books
In the A Song of Ice and Fire novels, there is no character named Bianca and it is unknown which actress portrays Sansa. It is Arya, under her guise of "Mercedene" (a.k.a. "Mercy"), who plays the role of a young, sweet maiden who gets raped and murdered by the dwarf, performed by Bobono, in The Bloody Hand.