Courtesans could be considered to be at the pinnacle of the prostitution hierarchy and a person who engages their services may not do so specifically for sexual reasons. Rather it is the pleasure and honour of their company that is paid for.
Engaging their company bestows as certain amount of status on the client themselves. In fact a sexual liaison may be the whim of the courtesan, not the patron. They are most likely similar to our world’s Japanese geisha, educated and trained in various cultural pursuits such as music, poetry, dance, history, literature etc.
Braavos is also renowned worldwide for its courtesans, they enjoy high status and are famous worldwide.
Every courtesan has her own barge and servants to work them. The beauty of famed courtesans has inspired many a song. They are showered with gifts from goldsmiths and craftsmen beg for their custom. Nobility and rich merchants pay the courtesans large amounts of money to appear alongside them at events, and bravos are known to kill each other in their names.
Some Braavosi courtesans are famous, respected and wealthy and enjoy a kind of celebrity status as well as a certain kind of mystique. They are cultured and beautiful.
Would you sooner be a courtesan, and have songs sung of your beauty? Speak the word, and we will send you to the Black Pearl or the Daughter of the Dusk. You will sleep on rose petals and wear silken skirts that rustle when you walk, and great lords will beggar themselves for your maiden’s blood.
- The Black Swan - was a celebrated courtesan, and was eventually ruler of Lys, in all but name.
- Bellenora Otherys - the second Black Pearl of Braavos, bastard daughter of Aegon IV Targaryen and Bellegere Otherys
- Bellonara Otherys - former Black Pearl and mother to the current Black Pearl
- Bellegere Otherys - current Black Pearl
- The Veiled Lady
- The Merling Queen
- The Moonshadow
- The Daughter of the Dusk
- The Nightingale
- The Poetess
A Feast for Crows
When Cat is talking to some Westerosi sailors off of the Brazen Monkey the youngest monkey, a red-haired boy with freckles no older than sixteen, asks her “What about them fancy whores the singers sing about?" His shipmates look at him and laugh. One of them says,
Seven hells, boy. Might be the captain could get hisself a courty-san, but only if he sold the bloody ship. That sort o’ cunt’s for lords and such, not for the likes o’ us. 
Cat tells them that she sold three cockles to the Black Pearl, she called to Cat as she was stepping off her barge.
As she pushes her barrow along the canals Cat sometimes glimpses one of them floating by, on her way to an evening with some lover. 
The courtesans of Braavos were famed across the world. Singers sang of them, goldsmiths and jewelers showered them with gifts, craftsmen begged for the honour of their custom, merchant princes paid royal ransoms to have them on their arms at balls and feasts and mummers shows, and bravos slew each other in their names.