Sarella Sand

Sarella Sand is an unseen character in the fourth season. She is first mentioned in "First of His Name".

Background
Sarella Sand is the fourth of the eight bastard daughters of Prince Oberyn Martell.

Season 4
Oberyn mentions his eight bastard daughters to Queen Cersei.

In the books
In the A Song of Ice and Fire novels, Sarella is Oberyn's daughter whom he fathered on a ship captain from the Summer Islands. Her mother is the captain of the Feathered Kiss.

She is nearly twenty years old, and has a reputation for insatiable curiosity and "pushing in where she didn’t belong".