Elyes Cherif Gabel (/ˈɛliəs ɡəˈbɛl/; born May 8, 1983) is a British actor. Gabel's global breakout role was portraying computer genius Walter O'Brien in the CBS series Scorpion (2014–2018). Earlier he gained recognition as series regular Dr. Gurpreet "Guppy" Sandhu in the BBC medical drama Casualty (2004–2007), as Dothraki Rakharo in seasons 1 and 2 of the HBO series Game of Thrones (2011–2012), as PE teacher Rob Cleaver in series 4 of BBC One's school-based drama series Waterloo Road (2009) and as DC Jose Rodriguez in the ITV drama Identity (2010).