Obara Sand

Obara Sand is a character set to appear in the fifth season, who had already been alluded to in the fourth season. She will be played by Keisha Castle-Hughes.

Background
Obara Sand is the eldest of the eight bastard daughters of Prince Oberyn Martell, known as the "Sand Snakes". Her mother was a peasant from the Reach.

Even more than her other sisters, Obara inherited her father's martial prowess, particularly his skill with a spear. Obara is a very tough warrior and the most overtly martial of the Sand Snakes. The other Sand Snakes will change out of their light leather armor when traveling in the hot deserts of Dorne, but Obara always wears her leather armor. When she sees an obstacle, she does not attempt to undermine it with deception or intrigue, but will attack it head-on relying on the strength of her weapons. This is in contrast with her sister Nymeria, who prefers to hold off and analyze her foes to calculate a more efficient means of defeating them.

Obara is the Sand Snake most like their father. He taught her the ways of war himself, training her in the use of a traditional Dornish spear like he used. She is staunchly disciplined to not overtly display many emotions besides anger.

Season 4
Oberyn mentions his eight bastard daughters to Queen Cersei Lannister while the two discuss Cersei's own illegitimate daughter Myrcella Baratheon, who has been sent to Dorne.

In the books
In the A Song of Ice and Fire novels, Obara is Oberyn's daughter whom he fathered on a whore in Oldtown. She is the least pretty and the most aggressive of all the Sand Snakes.

When her father came to claim her, her mother did not want him to take her. He threw a spear down at her mother's feet and slapped her mother. Then Oberyn asked Obara which weapon, the spear or the tears, Obara chose the spear. Her mother drank herself to death within a year.

She is prickly, hot-tempered woman who is given to martial pursuits as she considers herself a warrior, wielding a spear, a whip, and a round shield of steel and copper. She is hard, quick, and strong. She is fond of wine and is a confident rider who uses spurs, often to the point where the animal is bloody, and always rides stallions. Obara is a big-boned woman near to thirty, long-legged, with close-set eyes and rat-brown hair.

Obara in the books is the daughter of a whore from Oldtown in the Reach, but the casting announcement stated that TV-Obara is the daughter of a "Dornish peasant girl" that caught Oberyn's eye. The difference is not particularly drastic, but it might alter Obara's complex relationship with Oberyn - though the general point stands that Obara's mother wasn't of noble birth, unlike the mothers of some of the other Sand Snakes such as Nymeria Sand.

Either way, Obara in the books generally resembles other "salty Dornishmen". Keisha Castle Hughes is herself half-Maori.