Jürgen Prochnow (German pronunciation: [ˈjʏʁɡn̩ ˈpʁɔxnoː] ; born 10 June 1941) is a German actor. His international breakthrough was his portrayal of the good-hearted and sympathetic U-boat Commander "Der Alte" ("Old Man") in the 1981 war film Das Boot.

He is also known for his roles in The Lost Honour of Katharina Blum (1975), Dune (1984), Beverly Hills Cop II (1987), Twin Peaks: Fire Walk with Me (1992), In the Mouth of Madness (1994), The English Patient (1996), Air Force One (1997), The Da Vinci Code (2006), and for playing Sergei Bazhaev on the eighth season of 24 (2010). He is a Goldene Kamera, Bavarian Film Awards, and Bambi Award winner.