Sandor Clegane, better known as "The Hound" is a warrior initially under the employ of the Lannisters. He is referred to as the Hound, which is a reference to the sigil of House Clegane, three black dogs on a field of yellow. He left the lands of House Clegane when Gregor inherited. Their father died under suspicious circumstances. Sandor left and took service with the Lannisters. When the series begins, he works as a protector for Joffrey Baratheon. After the death of Robert Baratheon, Joffrey becomes king and he wants Sandor named to the Kingsguard. He is the brother of Gregor Clegane, whom he hates. Sandor is easily recognized because half of his face was severly burned by Gregor when they were children; this event spurred a fear of fire in Sandor. Many times Sandor Clegane has been offered knighthood, but he has always refused. Gregor Clegane, the monster became a knight and Sandor lost all respect for the institution.
In A Game of Thrones, Sandor kills a butcher's son named Mycah, who is Arya Stark's friend, after he is accused of attacking Prince Joffrey. This is not true, and Arya despises Sandor, naming him in her nightly ritual of enemies she plans to kill someday.
In the capital Sandor Clegane defends Ser Loras at the Hand's Tournament when Gregor tries to kill him. Ser Loras names Sandor the champion and he collects a prize of 20,000 dragons. Escorting Sansa back to the Red Keep after the Tounament feast, Sandor tells her how he got burned, but warns her that he will kill her if she tells anyone else.
When Sansa Stark becomes a captive of the Lannisters, he routinely haunts and protects her. When Joffrey takes Sansa to see her father's head on the walls of the Red Keep, Sansa thinks about pushing Joffrey to his death, but Sandor gets between them, saving her from an execution for kingslaying. At Joffrey's name day tournament he seconds her story that it is bad luck to order someone executed on your name day. Sansa has said Joffrey can't have Ser Dontes killed for being drunk. He gives Sansa his cloak when Joffrey has her stripped and beaten for Robb's victories.
On the night of the Battle of the Blackwater in A Clash of Kings, Tyrion Lannister orders him to ride out into fields of wildfire. Sandor refuses and secretly visits Sansa. He frightens her by throwing her down on a bed and holding a knife to her throat. He makes her sing a song to him. She sings him a hymn to the Mother and he releases her. Although he does not kiss her, Sansa thinks that he is about to, and later edits her memory to include a kiss. After he rips his white cloak from his back and leaves it in Sansa's chamber, he escapes from King's Landing.
In A Storm of Swords, the Hound is captured by the Brotherhood without Banners at the same time Arya is captured. The brotherhood wishes to make Sandor pay for his crimes, and Arya accuses him of killing Mycah. Sandor participates in a trial by battle for himself against Beric Dondarrion, the lightning lord. Sandor manages to beat Beric (who, of course, survives) but sustains wounds, and asks the brotherhood to help him. They take his prize winnings from the tournament, but allow him to leave.
Later on, Arya is captured by him. Sandor plans to take her to Robb and Catelyn Stark at the castle of Walder Frey. Sandor wants a ransom, but the two of them arrive at the Red Wedding just as the chaos there is unfolding. Arya wants him to help her save her mother, but Sandor hits her on the back of the head and escapes with her in the confusion. They ride together across Westeros, with Sandor looking for anyone to ransom her to. For a time he works building defenses in a village on the way to the Vale of Arryn. At the end of the book, Sandor and Arya come across the crossroads inn, where they meet Polliver, the Tickler, and a young boy. The Hound and Arya kill the three men, but the Hound is gravely wounded and cannot continue. Eventually, he lays under a tree to die, and asks Arya for the gift of mercy. She tells him that he doesn't deserve it, and then rides off on her own.
In A Feast for Crows, it is reported that the Hound is working with Beric's men and was involved in an incident at Saltpans where many people were slaughtered. Near the end of the novel, however, Brienne of Tarth goes to the Quiet Isle, where she meets a septon who claims to have buried Sandor and left his helm on a cairn, where it was stolen. Rorge, one of the men who was supposed to go to Wall with Yoren, stole the helm and wore it for his own. Many fans believe that Sandor became the gravedigger at the Quiet Isle, but this is not proven. After Brienne kills Rorge, the outlaw Lem of Lemonwood with the yellow cloak wears the Hound's helm.
Sandor is known as a cruel and ruthless man, but he may choose to hide his more pleasant emotions. He wants to kill his brother and despises knighthood and seems to be the antithesis of the stereotypical white knight.