Sam Witwer Samuel Stewart " Sam " Witwer ( born October 20 , 1977 ) is an American actor . Biography . Early life . Known to his friends as " Stew " , Witwer grew up in , , a small suburb town of . There , he attended Glenbrook South High School and became involved in theater as well as becoming the lead singer in a band called " Love Plumber " . After receiving marks that were less than satisfactory , Witwer later attended the for drama stating that it was the only school that accepted him on the fact that they didn ' t look at his transcripts . Career . Witwer ' s first on - screen credit was for a Chicago Bulls commercial . His first major role was in science fiction show " " . He also made an appearance on " " . From 2008 to 2009 , Witwer had been cast as for the eighth season of " " . His character was a charming paramedic that doubles as the show ' s incarnation of . Although uncredited , he also portrayed in the last scene of the Season eight finale while the character would be portrayed by British actor for the duration of the show ' s ninth season . In 2010 he starred as a walker in the pilot episode of AMC ' s The Walking Dead . From 2011 to 2014 , Witwer portrayed the lead vampire Aidan in the Syfy Channel ' s remake of the BBC original series " " . From 2016 , he portrays Mr . Hyde from the sixth season in the ABC series " Once Upon a Time " . " Star Wars " work . When Amy Beth Christenson ' s original concept art of Galen Marek looked strikingly like Sam Witwer , the vice president at the time noted the resemblance due to recognizing Witwer for " Battlestar Galactica " so he was contacted to audition . From there , he became the complete basis for the main character ' s voice and appearance in " " . His likeness was created through motion capture for the game to build the character ' s appearance and range of facial expressions . Witwer ' s performance was recorded on HD cameras ( as were all the actors who worked on the game ) . While the game was in production , Witwer only knew his character as " Starkiller " . Witwer also voiced Galen Marek ( known only as " The Apprentice " ) in " Soulcalibur IV " . Witwer returned to play Starkiller in the sequel " " . For this character , he served in the same capacity as before by providing his voice and likeness to the main character . Witwer also voiced Palpatine in " Star Wars : The Force Unleashed " , and gave his voice and likeness to the imperfect genetic replicas and the Dark Apprentice in " Star Wars : The Force Unleashed II " . Afterwards , Witwer appeared on the " " television series as the voices of the Son and Darth Maul . Witwer took over voicing Palpatine from Tim Curry for the second season of " Star Wars Rebels " . Witwer voiced various characters in , including several stormtroopers , an announcer and First Order officer . Witwer also provided additional voices in " " . Behind the scenes . Witwer is also lead singer of the band The Crashtones . Witwer has expressed an interest in being in the , presumably reprising his role as Galen Marek . He recently appeared in " Star Wars Rebels " , reprising his role as Emperor Palpatine , whom he voiced in both " The Force Unleashed " , " The Empire Strikes Out " and " Kinect Star Wars " . Witwer is a huge Star Wars trivia nerd and has participated in trivia competitions such as the Star Wars Movie Trivia Schmoedown and is the current Star Wars champion .