A famous opera singer of the Scala of Milan, Bianca Castafiore is the only female character of any importance in Tintin's universe. She possesses a clearly hysterical temperament and is not exactly modest. Aside from her limited musical repertoire (she always sings the same Tune of Jewels from Faustus, by Gounod), she seems to be very educated. She is very emotional and faints at the smallest threat. Very narcissistic, Castafiore sees only herself and doesn't really notice other people's reactions. She even invites herself to Marlinspike and moves in for a while.

The Diva seems to be heedless; she can not pronounce well the name of The Captain even Nestor's and Jolyon Wagg's. She also thinks that Calculus is a well-known sportsman.

Her relationships with the other characters are a bit muddled. Still, Calculus is immediately taken with the diva. With such a conversationalist, it matters little that the conversation makes no sense at all, since everybody is deaf in his own way.