Horak emigrated to the United States in 1951 with his parents and twin brother. After schooling in Chicago, he returned to Germany with his family in 1964. Gratuating from Frankfurt American High School, he attended Ohio University, University of Delaware (B.A.), and Boston University (M.S.), before completing a PhD. at the University of Muenster in Germany. His career as a film archivist, restorationist, and historian has taken him from George Eastman House (1984-1994) to the Munich Filmmuseum (1994-1998), Universal Studios (1998-2000), and the Hollywood Entertainment Museum (2000-2006). In December 2007 he was appointed Director, UCLA Film & Television Archive. He has taught at a number of universities, including the University of Rochester, the University of Salzberg, the Munich Film Academy, and UCLA. He has published ten books and over 200 articles in ten languages on various film historical topics.