He is a former slave-trader from the city of Meereen, on the coast of Slaver's Bay, and a scion of the House of Loraq, an ancient and proud line of slavers.
Hizdahr belongs to the ancient aristocratic House of Loraq, who have been one of the ruling families of slavemasters in Meereen for many generations.
Hizdahr zo Loraq is fluent in the Common Tongue of Westeros, which is not unusual for merchants in Essos, as they take part in long-distance trade.
Hizdahr zo Loraq is the son of one of the many Great Masters. He, along with his father and the rest of Meereen's nobility, gather over the walls of the city when Daenerys Targaryen and her army appear before the city gates to lay siege to it.
His father is crucified in the aftermath of the siege, a matter which he later confronts her about personally. Hizdahr pleads to be allowed to bury him at the Temple of the Graces, to which she agrees, after learning that he had opposed the crucifixion of the slave children as an ill-conceived warning against Daenerys.
Some weeks later, Daenerys tells Jorah Mormont to send Hizdahr to Yunkai as her ambassador. Hizdahr is to offer the Wise Masters a choice: they can "live in her new world" and accept the abolition of slavery, or "die in their old one" at the hands of the Second Sons sent under the command of Daario Naharis.
Hizdahr and Daario return to Meereen to find the Unsullied patrolling the streets in response to attacks by the Sons of the Harpy. Hizdahr is initially happy to report that the Wise Masters have agreed to have Yunkai governed by a council of freed slaves and former Masters. They have even agreed to submit their important decisions to Daenerys for authorization. However, they insist that the city's infamous fighting pits be reopened. Daenerys is furious at this concession and refuses, even though the Wise Masters have agreed that all fighters will be free men who enter the arena willingly. Hizdahr is frustrated when Daenerys ends the argument by declaring that she is a queen, not a politician
Hizdahr later becomes a member of Daenerys's small council, representing the former Great Masters. After White Rat's killer is caught, he and Mossador butt heads over what to do with him. Hizdahr disagrees with Mossador's insistence that the Sons of the Harpy are funded by the Great Masters. Mossador ultimately kills the murderer without Daenerys's consent, and Hizdahr witnesses his execution, voicing his opinion that Daenerys should have killed Mossador inside the pyramid with few witnesses instead of publicly executing him.
On the day that usually marks the traditional opening of the fighting season Hizdahr again entreats Daenerys to reopen the fighting pits, noted that while it is not a perfect solution, it will at least be enough to bring the Meereenese and Yunkish Masters to the table.
Following the skirmish that claimed the life of Ser Barristan Selmy, Hizdahr visits Daenerys to offer his condolences. He and Daario offer advice on how to deal with the Sons of the Harpy, but Daenerys coolly informs them that she will take the heads of Meereen's great houses into custody. When Hizdahr points out that this description applies to him, the Unsullied grab him immediately. Hizdahr and the other heads of house are brought into the catacombs. As the Unsullied drive them forward, Daenerys explains that she has no idea which of them are guilty and which are innocent (including Hizdahr). When Rhaegal appears and roasts one of the Great Masters alive, Hizdahr is the only one of the remaining Masters to remain standing, offering as his defense a halfhearted "valar morghulis". Daenerys, having reminded the Great Masters of what she (and her dragons) can do, allows them to leave with their lives, but keeps them under arrest. Later, she visits Hizdahr in his cell. His composture now gone, he prostrates himself before her and begs for mercy, as he is terrified. Daenerys is pleased that he's now being honest again, and informs him that in the interests of peace she will reopen the Fighting Pits (to free men only). She will also show her respect for Meereen by marrying a member of one of its great families – and fortuitously, she already has one of them on their knees before her.
The Sons of the Harpy attacks cease following the betrothal, which brings Daario to believe that Hizdahr may be involved with them, though Daenerys remains unconvinced. Hizdahr and Daenerys visit a fighting pit in order to honor the lesser pit fighters with their presence. Though Daenerys soon desires to leave when she is disturbed by the violence, Hizdahr persuades her to stay in order to respect traditions. He witnesses Jorah Mormont and Tyrion Lannister reveal themselves to Daenerys in the pit.
During the Great Games, the Sons of the Harpy attack Daznak's Pit. Hizdahr attempts to lead Daenerys to safety, but is grabbed and stabbed repeatedly in the chest by four members of the Sons of the Harpy, indicating that he had been loyal to Daenerys after all.
Hizdahr was a Meereenese nobleman who advocated that Daenerys respect local traditions, specifically the ancient fighting pits. She took his advice when she reopened the city's fighting pits and even offered to marry him. Although Daario Naharis suspected Hizdahr was behind the Sons of the Harpy, Hizdahr was killed by the rebel group at the Fighting Pit of Daznak.