Question: What fictional character that fights terrorism is played by the actor who played a Dothraki in seaons 1 & 2 of Game of Thrones?

Context paragraphs:
Elyes Gabel: Elyes Cherif Gabel (born 8 May 1983) is an English actor.  Among his most notable roles, he has portrayed Dr. Gupreet "Guppy" Sandhu in the "BBC" medical drama "Casualty", Dothraki Rakharo in Seasons 1 and 2 of the "HBO" series "Game of Thrones", and P.E. teacher Rob Cleaver in the BBC drama "Waterloo Road".  He appeared in the "ITV" drama "Identity" and portrayed Detective Adam Lucas in Season 3 of "Body of Proof".  He is currently starring in the CBS series "Scorpion" as computer genius Walter O'Brien.

Dothraki language: The Dothraki language is a constructed fictional language in George R. R. Martin's fantasy novel series "A Song of Ice and Fire" and its television adaptation "Game of Thrones", where it is spoken by the Dothraki, nomadic inhabitants of the Dothraki Sea.  The language was developed for the TV series by the linguist David J. Peterson based on the Dothraki words and phrases in Martin's novels.

Walter O'Brien (character): Walter O'Brien is the fictional lead character in the American drama television series, "Scorpion".  The character is inspired by the real life of Walter O'Brien, a computer expert and hacker who at an early age hacked into NASA servers to obtain secure files and scored a 197 on a childhood IQ test.  The character, played by actor Elyes Gabel, follows a loose trajectory of Walter O'Brien's real-life exploits that thwart terrorism and disasters in each episode of the series.

Millia Rage: Millia Rage (Japanese: ミリア＝レイジ , Hepburn: Miria Reiji ) is a fictional character in Arc System Works's "Guilty Gear" video game series.  She first appeared in the 1998 video game "Guilty Gear".  In the series, Millia is a retired assassin who fights with her own hair, which is prehensile and able to change its size and shape.  This ability of manipulate her hair has been received with both praise and criticism by video game reviewers who have commented on the character with mostly positive statements.

Ned Stark: Eddard "Ned" Stark is a fictional character in the 1996 fantasy novel "A Game of Thrones" by George R. R. Martin, and the first season of "Game of Thrones", HBO's adaptation of Martin's "A Song of Ice and Fire" series.  In the storyline, Ned is the lord of Winterfell, an ancient fortress in the North of the fictional continent of Westeros.  Though the character is established as a primary character in the novel and the TV adaptation, Martin's plot twist at the end involving Ned shocked both readers of the book and viewers of the TV series.

Olenna Tyrell: 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).

Gregor Clegane: 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).

Gendry: 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.

Margaery Tyrell: 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).

Shannon Ritch: Shannon Grey Ritch (born September 27, 1970) is an American professional mixed martial artist, boxer, professional wrestler and kickboxer, known for being the former Gladiators Challenge Heavyweight Champion and KOTC Middleweight Champion also current RUF Interim Heavyweight Champion and IFC Middleweight Champion.  A professional competitor since 1998, Ritch has competed for the MFC, Pancrase, K-1, PRIDE, Rebel Fighting Championship, King of the Cage and the WEC.  Ritch has also has been featured in two episodes of Walker, Texas Ranger as a Biker Gang Member and a character named Knight, Choke in 2011 as an extra, CSI Las Vegas as Thug #2, an episode of iCarly as a MMA Fighter, an episode of Numbers in 2010, an episode of Ultimate Soldier Challenge on the History Channel representing a military contracting company and most recently in 2017 the direct to DVD film, directed by Robert Parham, Bullets, Blades and Blood and upcoming in 2018 No Way Out directed by Jeffrey D. Parker.  Shannon claims he has over 200 professional MMA fights 112 wins, 88 losses and 2 draws, some fights going undocumented and dating back as far as 1991.  His documented record of fights goes back to 1998 with a record of 56 wins, 81 loses, and 4 draws.  Shannon also holds a 2-1 record in professional boxing and a 25-2 record in bare knuckle boxing with all of his wins coming by way of knockout, in 2017 he was inducted into the Bare Knuckle Boxing Hall of Fame and also plans to round out his boxing career in 2018 against boxing superstar Bobby Gunn.  Ritch is also an occasional professional wrestler, recently in mid 2017 main eventing a card in Guyana.  Shannon has also found success as a grappler winning multiple NAGA, Grapplers Quest and Abu Dhabi Combat Club competitions, most recently winning a gold medal in the super heavyweight division at the Grand Canyon 2017 BJJ Open in Arizona and a silver medal at the '17 Arizona State BJJ Championships.  Ritch is also an avid golf player, winning 1st place in many state and pro am competitions held within his native Arizona as recent as 2017.

Supporting paragraphs: Walter O'Brien (character) Elyes Gabel
Answer: Walter O'Brien