After memorable guest-star turns on popular series, including "Numb3rs", "Walker Texas Ranger", ' and ', Martini landed a lead role on "The Unit", a series about a tier-1 US Army special operations team created by David Mamet and produced by Shawn Ryan of "The Shield". Martini remains active in the theater, having co-founded the Theatre North Collaborative in New York City, a company of American and Canadian actors dedicated solely to producing new works from both sides of the border. In 2011, he appeared in an episode of "Criminal Minds", in which he played a Navy SEAL named Luke Dolan.