Bianca Castafiore
Debut: King Ottokar's Sceptre
There is a great paradox about Bianca Castafiore, the
Milanese Nightingale. This singer who is adulated around the world, this
diva among divas whose singing is broadcast to the most remote corners
of the globe, is not appreciated in the slightest in The Adventures of
Tintin. All of Hergé's characters seem allergic to her voice, with
the possible exception of Professor Calculus, but then he is deaf. 
The only woman of importance in a world of men, Bianca Castafiore seems at first to bring nothing but trouble to the series. As soon as she appears, everything becomes confused and tangled. Her relations with the other characters are more complex than one might think.
In The Castafiore Emerald, it is obvious that Professor Calculus is in love with her. As for Nestor the butler, he is clearly embarassed when she promises to send him a signed photograph. And even Captain Haddock, whom one could have swore despised her, seems to be more affected than he would admit: the first time he meets the diva (backstage in the Szohod Opera House) he loses his composure completely and is unable to introduce himself. No wonder, therefore, that subsequently the singer invariably gets his name wrong.
The comic side to her character should not obscure the fact that Bianca Castafiore is a loyal ally of Tintin and Haddock; as when in The Calculus Affair she hides them in her dressing room without asking any questions. Some might say that she simply wanted to join them in the game, but it is more likely that she felt she was part of the team.