George R.R. Martin's A Song of Ice and Fire books feature several point-of-view characters that were cut out of the Game of Thrones show.
Martin's books are known for alternating between points of view after each chapter. Over the course of the series, there are 31 different characters we see A Song of Ice and Fire's events through. Although most of these characters, like Arya Stark, Daenerys Targaryen, and Jon Snow, were clearly main components of the show, several important characters were cut out entirely.
Victarion Greyjoy
Victarion Greyjoy is the younger brother of Balon Greyjoy, who vies for the Ironborn crown after his older brother's death. He is constantly at odds with his other brother, Euron, who wins the support of the Ironborn and becomes their leader, much to Victarion's dismay.
Euron eventually sends Victarion to Slaver's Bay with a marriage proposal, but he secretly plans to marry Daenerys himself. Euron also gives him a horn called Dragonbinder, which is allegedly supposed to make any dragon loyal to the horn's owner. Along the way, Victarion used the iron fleet to capture other ships and slaves, including a red priest named Moqorro, who heals Victarion's injured hand. Moqorro begins to convert Victarion to the faith of the Red God R'hollor.
Varamyr Sixskins
Varamyr Sixskins is a Wildling warg who serves as the point of view in the prologue chapter of A Dance with Dragons. This is one of the most unique chapters in the entire series for a lot of reasons, the primary being that Varamyr is the most powerful warg we know of. He has the ability to control six different animals simultaneously, including a polar bear, a shadowcat, a hawk, and three wolves.
Varamyr is also Mance Rayder's second-in-command, which made it even more frustrating that he didn't make it into the show. The chapter also details the final moments of Varamyr's life, as he succumbs to the wounds he sustained when Stannis Baratheon's army attacked the wildlings. As he dies, we get a lot of details on the logistics of warging, which could be foreshadowing for Jon Snow's eventual resurrection.
Arianne Martell
Arianne Martell is the daughter of Doran Martell, the leader of the desert kingdom of Dorne. Much of Arianne's initial chapters revolve around her insecurity with her position as the heir of Dorne, as she believes that her father will name her younger brother as heir. This leads her to plot against her father and plan to crown Myrcella Baratheon as the queen of the Seven Kingdoms.
After her plan is foiled, Doran reveals that he never intended to betray Arianne, but he wanted to betray the Lannisters and help the Targaryens return to power. A sample chapter from The Winds of Winter reveals that Doran sends Arianne to meet with Aegon Targaryen, who had just landed an army of sellswords in the Stormlands.
Arianne is a cool character who could have a major role in future books, but it's not surprising that she was cut from the show. Much of the plotlines involving the Dornish characters were completely changed, removed, or whitewashed in the show.
Quentyn Martell
Like Arianne, Quentyn Martell is one of Doran's children. Quentyn has a lot of similar character qualities to Samwell Tarly, as they both have heroic desires but lack the courage and ability to act on their fantasies. Quentyn is described as "not handsome," and his POV chapters are full of his doubts and insecurities.
He's a relatable character, especially because he tries in vain to seduce Daenerys Targaryen. After Daenerys leaves the city on Drogon's back, Quentyn attempts to tame one of her other dragons to prove that he can be Daenerys' queen. This ends in him being burned alive in A Dance with Dragons, leaving Dorne's potential alliance with Daenerys in limbo.
Arys Oakheart
Arys Oakheart was one of Robert Baratheon's Kingsguard knights. Unlike the other Kingsguard, Arys regrets the fact that he is ordered to beat Sansa Stark, and he is relieved when he is chosen to escort Myrcella Baratheon to Dorne.
Arys becomes a POV character for a brief time in A Feast for Crows, where he is being seduced and manipulated by Arianne Martell to assist in her plot to crown Myrcella. When the plot is discovered by Doran Martell, his forces capture Arianne's retainers before they are able to act on their conspiracy. Arys attempts to fight the Dornishmen, but is surrounded and killed by Areo Hotah.
Aeron Greyjoy
Aeron Greyjoy is the youngest brother of Balon and a priest of the Drowned God. Aeron claims to be a prophet, but he never makes any prophecies, and his devotion to religion seems to be a coping mechanism for childhood abuse and alcoholism. After Euron is crowned the leader of the Iron Islands, Aeron is captured by Euron and dosed with a psychedelic drug, which forces him to see calamitous visions and remember the childhood abuse at the hands of Euron.
Like the Dornish plots, Aeron's story is unnecessary for the show because Euron is an entirely different character. He is not the menacing villain he is in the books, so Aeron's perspective isn't as needed in the show.
Jon Connington
Jon Connington served as the Mad King's Hand during the end of Robert's Rebellion. Connington had a close bond with Rhaegar Targaryen, and it is heavily implied that he was in love with the prince. After Robert Baratheon defeated Connington at the Battle of the Stony Sept, the Mad King banished Connington from Westeros.
Connington, going by the name Griff, becomes a point-of-view character in A Dance with Dragons, where he helps a boy that we are led to believe is Rhaegar's son Aegon. Everyone is under the impression that Aegon was killed by the Mountain during the sack of King's Landing, but Varys allegedly smuggled him out of the city.
Connington grooms the boy to become king of Westeros and secures support for his claim. These efforts culminate near the end of the fifth book, when Aegon invades Westeros with a sellsword group called the Golden Company.