Josefin Hagen is a German actress, singer, and voice actress born in 1982. She began her performance career in theater as a teenager, appearing in a 1994 production of Medea. Her early training took place at the Theaterstudio Friedrichstraße in Berlin, and she subsequently performed at several prominent theaters in Germany, including the Schauspiel Essen, the Theater am Kurfürstendamm in Berlin, and the Komödie Winterhuder Fährhaus in Hamburg, a career phase that lasted until approximately 2002. Alongside her acting work, Hagen pursued studies in jazz, rock, and pop vocals at the Berlin University of the Arts and the Music College in Regensburg starting in 2005. She also formed a band called Josefin lost in lines, which performed at the Deutscher Rock und Pop-Preis in 2012.

Since 2008, Hagen has been active as a voice actress for film and television productions, lending her voice to numerous characters in both live-action and animated series. In the realm of anime, she is known for several German dubbing roles. She voices Momo Belia Deviluke in the anime series To Love Ru and its sequel To Love Ru Darkness, providing the German voice for the character originated by Japanese voice actress Aki Toyosaki. Her work also includes the role of Sassa Kurasaki in the 2017 series Armed Girl's Machiavellism. Additionally, she was the first German voice for the character Nicole Spears in the 2012 series BeyWheelz: Powered by Beyblade.

Beyond her work in anime, Hagen's extensive voice career includes dubbing for a wide array of live-action television series and films. She is notably the regular German voice for actresses such as Holland Roden, known for her role as Lydia Martin in Teen Wolf, Haley Tju, and Gia Mantegna. Her other dubbing credits include providing the German voice for characters in series like Mad Men, Grey's Anatomy, and Under the Dome. In addition to her voice work, she has appeared as an on-screen actress in German television productions, including a role in the long-running series Gute Zeiten, schlechte Zeiten in 2019.