Question: Walter O'Brien was played by which English actor?

full_context: Document 1: Gabe Kaplan: Gabriel Weston "Gabe" Kaplan (born March 31, 1945) is an American comedian, actor, poker commentator, and professional poker player.
Document 2: 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.
Document 3: Bradley Walsh: Bradley John Walsh (born 4 June 1960) is an English actor, comedian, singer, television presenter and former professional footballer, best known for his roles as Danny Baldwin in "Coronation Street" and the lead role of in "", as well as hosting ITV game shows "The Chase" and "Cash Trapped".
Document 4: James Callis: James Nicholas Callis (born 4 June 1971) is an English actor. He is best known for playing Dr. Gaius Baltar in the re-imagined "Battlestar Galactica" miniseries and television series, and Bridget Jones' best friend in "Bridget Jones's Diary" and "". He later reprised the role in 2016, in "Bridget Jones's Baby." He joined the cast of the TV Series "Eureka", on Syfy, in 2010. In 2017 he voiced the character Alucard on the Netflix series "Castlevania", based on the video game of the same name.
Document 5: Mr Smith (The Sarah Jane Adventures): Mr Smith is a fictional extraterrestrial computer voiced by Alexander Armstrong which appears in the British children's science fiction television series, "The Sarah Jane Adventures", with further minor appearances in the final two episodes of the fourth series of "Doctor Who". He is installed in the attic of Sarah Jane Smith's home, and is used to hack into other systems; Sarah Jane asserts that he can hack "into anything". He first appeared in "Invasion of the Bane", the 2007 New Year's Day première special, and has appeared in all the stories except "The Eternity Trap" and "Lost in Time".
Document 6: Howard Wolowitz: Howard Joel Wolowitz, M.Eng. is a fictional character on the CBS television series "The Big Bang Theory", portrayed by actor Simon Helberg. Among the main male characters in the show, Howard is distinctive for being an engineer rather than a physicist and lacking a doctoral degree.
Document 7: Walter White (Breaking Bad): Walter Hartwell White Sr., also known by his clandestine alias Heisenberg, is a fictional character and the main protagonist of "Breaking Bad". He is portrayed by Bryan Cranston. A graduate of the California Institute of Technology, Walt was once a promising chemist who cofounded the company Gray Matter Technologies with his close friend Elliot Schwartz and his then-girlfriend Gretchen. He left Gray Matter abruptly, selling his shares for $5,000; soon afterward, the company made a fortune, much of it from his research. Walt subsequently moved to Albuquerque, New Mexico, where he became a high school chemistry teacher. "Breaking Bad" begins on Walter's 50th birthday, when he is diagnosed with Stage IIIA lung cancer. After this discovery, he resorts to manufacturing methamphetamine and drug dealing to ensure his family's financial security after his death. He is pulled deeper into the illicit drug trade, becoming more and more ruthless as the series progresses, and later adopts the alias "Heisenberg", which becomes recognizable as the kingpin figure in the local drug trade. Series creator Vince Gilligan has described his goal with Walter White as "turning Mr. Chips into Scarface", and deliberately made the character less sympathetic over the course of the series. Walt's evolution from mild-mannered school teacher and family man to ruthless criminal mastermind and murderer is the show's central focus.
Document 8: Chuck (TV series): Chuck is an American action-comedy/spy-drama television series created by Josh Schwartz and Chris Fedak. The series is about an "average computer-whiz-next-door" named Chuck Bartowski, played by Zachary Levi, who receives an encoded e-mail from an old college friend now working for the Central Intelligence Agency (CIA). The message embeds the only remaining copy of a software program containing the United States' greatest spy secrets into Chuck's brain, leading the CIA and the NSA to assign him handlers and use him on top-secret missions. Produced by College Hill Pictures, Fake Empire Productions, Wonderland Sound and Vision, and Warner Bros. Television, the series premiered on September 24, 2007, on NBC, airing on Monday nights at 8:00 p.m./7:00 p.m. Central.
Document 9: Mark Gatiss: Mark Gatiss ( ; born 17 October 1966) is an English actor, comedian, screenwriter and novelist. His work includes writing for and acting in the TV series "Doctor Who" and "Sherlock". Together with Reece Shearsmith, Steve Pemberton and Jeremy Dyson, he is a member of the comedy team "The League of Gentlemen". He is also known for his role as Tycho Nestoris in the HBO series "Game of Thrones".
Document 10: Creed Bratton (character): Creed Rowland Bratton, also known as "William Charles Schneider" (claims to have been born November 1, 1925) is a fictional character from the U.S. television series "The Office". Confusion may arise from the fact that the character is played by the musician of the same name, Creed Bratton. The fictional Creed is partially based on the experiences and former flower child lifestyle of the real one; however, the character is an embellished version of the real person. Unlike most characters of this version of "The Office", he has no equivalent in the original BBC series despite sharing similar lines in the pilot episode with the character of Ryan Howard. Series writer B. J. Novak has said that the actual Creed Bratton is exactly like the character he plays, except that the real Creed is a good-hearted and likable person, while his fictional alter ego has a very dark side to him. His resourcefulness and duplicity are his defining traits along with his senile behavior and ignorance of the modern world.
Document 11: 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.
Document 12: Scott Adkins: Scott Edward Adkins (born 17 June 1976) is an English actor and martial artist who is best known for playing Russian prison fighter Yuri Boyka in the 2006 film "" and its following two sequels: "" (2010) and "" (2016) and Casey Bowman in Ninja and its sequel . He is also known for playing Bradley Hume in "Holby City", Lucian in "Doctor Strange", Kiley in "The Bourne Ultimatum" and John in "Zero Dark Thirty". Adkins has also appeared in "EastEnders", "Hollyoaks", "Doctors" as well as starred in many direct-to-video films.
Document 13: Harry Lloyd: Harry Charles Salusbury Lloyd (born 17 November 1983) is an English actor. He is known for his roles as Will Scarlet in the 2006 BBC drama "Robin Hood", Jeremy Baines in the 2007 "Doctor Who" episodes "Human Nature" and "The Family of Blood", and Viserys Targaryen in the HBO series "Game of Thrones". He has also appeared on stage, and in films including "The Theory of Everything" and "Anthropoid".
Document 14: Gary McKinnon: Gary McKinnon (born 10 February 1966) is a Scottish systems administrator and hacker who was accused in 2002 of perpetrating the "biggest military computer hack of all time," although McKinnon himself states that he was merely looking for evidence of free energy suppression and a cover-up of UFO activity and other technologies potentially useful to the public. On 16 October 2012, after a series of legal proceedings in Britain, Home Secretary Theresa May withdrew her extradition order to the United States.
Document 15: Eli Wallace: Eli Wallace is a fictional character in the Canadian-American television series "Stargate Universe", a science fiction drama centering on the adventures of a present-day, multinational scientific team unable to return to Earth after an evacuation to the Ancient spaceship Destiny, which is traveling in a distant corner of the universe. He is portrayed by American actor David Blue. Blue auditioned for the role when he heard they were casting characters for the new show. Wallace is considered to be a slacker, yet at the same time a genius. Wallace made his first appearance in the pilot episode, "Air", first broadcast in the United States and Canada in 2009.
ground_truth: Elyes Gabel