High Sparrow

""All sinners are equal before the Gods.""

- High Sparrow's view on divine judgement High Sparrow (real name unknown) is a major character introduced in season 5 of Game of Thrones. He is the leader of a fundamentalist sect of The Faith of the Seven called The Faith Militant. Despite coming off as harmless and compassionate at first, he reveals his true colors as a fanatical zealot as the season progresses, usurping Cersei as the main antagonist of the King's Landing storyline. High Sparrow is arguably the tertiary antagonist of the season over all. He is portrayed by Jonathan Pryce, who also portrays General Vavarin Delatombe and Elliot Carver.

Ascension to Power
After talking with Lancel and hearing about the Faith Militant and High Sparrow, Cersei pays him a visit. His church had already raided and destroyed the former brothel of Petyr Baelish, showing the power they had already amassed in the area. She sees the kind old man feeding the poor, and notices the influence he has on the community. Instead of jailing him for what he did, she makes his group the religious authority of King's Landing. Seeking vengeance against house Tyrell, Cersei reveals that Loras is a homosexual and the Faith Militant arrests him. At his inquest, he denies being gay, and his sister Margaery claims this as well. The Faith bring in one of Loras' lovers, who says that he is indeed gay and that his sister walked in on them once. Because of this, the faith has both of them locked up (Margaery for lying under oath). Their grandmother Olenna confronts High Sparrow, and offers him various things in exchange for their freedom. High Sparrow Refuses, only caring about delivering what he views as justice. Olenna threatens that she will cease giving the capitol crops, and High Sparrow warns her that she is one of the few and not the many. Later, Cersei runs into him and the two discuss the upcoming trial for the Tyrell siblings. High Sparrow begins dropping hints that Cersei herself isn't innocent at all, and after Lancel appears (who Cersei had an incestuous affair with in season 1) she knows she is in trouble. The former queen cannot escape though, and is thrown into a cell by one of the faith militant. The High Sparrow having imprisoned both the queen and the king's mother, now had power over even the royal family. No one is King's Landing was safe any more from his crusade.

Trivia

 * High Sparrow shares some similarities to Melisandre. Both are priests willing to do extreme things to advance their religions. Both of them were given great power by royalty as well. The big difference is that Melisandre is in favor of sex and is not as pious. High Sparrow on the other hand gives all accused trials, and does not burn non believers alive.
 * High Sparrow's actor looks very close to the current Pope, Francis. Both are the head of their respective religions as well. Whether or not this casting was intentional or a coincidence is unknown.