Question: Which American actor is known for playing a fictional character in the "A Song of Ice and Fire" television adaptation "Game of Thrones"?

Context articles: Olenna Tyrell
Jon Snow (character)
Margaery Tyrell
Cersei Lannister
Jason Momoa
Davos Seaworth
Khal Drogo
Gregor Clegane
Jaime Lannister
Gendry

Olenna Tyrell (née Redwyne), also known as "The Queen of Thorns", is a fictional character in the "A Song of Ice and Fire" series of high fantasy novels by American author George R. R. Martin, portrayed by Diana Rigg in its television adaptation, "Game of Thrones".
 Olenna is first mentioned in "A Game of Thrones" (1996) and first appears in "A Storm of Swords" (2000).
Jon Snow is a fictional character in the "A Song of Ice and Fire" series of fantasy novels by American author George R. R. Martin, and its television adaptation "Game of Thrones".
 He is a prominent point of view character in the novels, and has been called one of the author's "finest creations" and most popular characters by "The New York Times".
 Jon is a main character in the TV series, and his storyline in the 2015 season 5 finale generated a strong reaction among viewers.
 Speculation about the character's parentage has also been a popular topic of discussion among fans of both the books and the TV series.
Margaery Tyrell is a fictional character in the "A Song of Ice and Fire" series of high fantasy novels by American author George R. R. Martin, and its television adaptation "Game of Thrones".
 Though a supporting character in the books, she played a more prominent role in the HBO series, and rose to become a main character eventually, where she is portrayed by Natalie Dormer.
 Margaery is first mentioned in "A Game of Thrones" (1996) and first appears in "A Clash of Kings" (1998).
Cersei Lannister is a fictional character in the "A Song of Ice and Fire" series of fantasy novels by American author George R. R. Martin, and its television adaptation "Game of Thrones", where she is portrayed by Lena Headey.
 In the novels, she is a point of view character.
Joseph Jason Namakaeha Momoa (born August 1, 1979) is an American actor, model, director, writer, and producer.
 He is known for his television roles as Ronon Dex on the military science fiction television series "Stargate Atlantis" (2004–2009) and as Khal Drogo in the HBO fantasy television series "Game of Thrones" (2011–2012).
Davos Seaworth, nicknamed the Onion Knight, is a fictional character from American novelist George R. R. Martin's "A Song of Ice and Fire" epic fantasy series.
 He is a point-of-view character in "A Clash of Kings", "A Storm of Swords" and "A Dance with Dragons" with a total of 13 chapters.
 He is portrayed by Irish actor Liam Cunningham in the HBO television adaptation "Game of Thrones".
Khal Drogo is a fictional character in the "A Song of Ice and Fire" series of fantasy novels by American author George R. R. Martin, and its television adaptation "Game of Thrones".
Gregor Clegane, nicknamed "The Mountain That Rides" or simply "The Mountain", is a fictional character in the "A Song of Ice and Fire" series of fantasy novels by American author George R. R. Martin, and its television adaptation "Game of Thrones".
 In the books, the character is initially introduced in 1996's "A Game of Thrones".
 He subsequently appeared in "A Clash of Kings" (1998), "A Storm of Swords" (2000) and in "A Dance with Dragons" (2011).
Jaime Lannister is a fictional character in the "A Song of Ice and Fire" series of fantasy novels by American author George R. R. Martin, and its television adaptation "Game of Thrones".
 He becomes a prominent point of view character in the novels beginning in "A Storm of Swords" (2000).
Gendry is a fictional character in the "A Song of Ice and Fire" series of fantasy novels by American author George R. R. Martin, and its television adaptation. "
Game of Thrones".
 He is a non-POV character, first appearing in 1996's "A Game of Thrones", and subsequently appeared in "A Clash of Kings" (1998), "A Storm of Swords" (2000) and "A Feast for Crows" (2005).
 Gendry is an apprentice blacksmith in King's Landing, and an unacknowledged bastard of King Robert Baratheon.