Lotan starred as Joe Farnetti in Foyle's War, a British drama set around real-life war stories in which characters must wage personal war amid the chaos of an actual war. He stated that his character in Foyle's War reminded him of a friend in the military who had an ability to see humor in any given situation. He voiced the lead role in the 2001 video game Operation Flashpoint: Cold War Crisis, as David Armstrong, a U.S. Army soldier serving in the Cold War. He appeared in the 2001 film, The Pool as Chris, played Kenny in the 2004 television series NY-LON, and acted next to Keira Knightley as an intern in 2005 film, The Jacket. Lotan also had a role in the fifth season of 24, as Spenser Wolff, and appeared in four episodes of CSI: NY as Marty Pino, a doctor/serial-killer. Lotan played Jesse in the 2006 film, One Night with the King, and was in the 2006 television film, The Beyond, centering on NASA Scientists at a jet propulsion laboratory during a global crisis. Lotan was also in the 2008 HBO historical war drama Generation Kill, as Robert Timothy Bryan, a U.S. Navy corpsman. He was also cast for the lead role in David Milch's HBO pilot Last of the Ninth.