Mario Hassert is a German voice actor and former disc jockey, born on February 28, 1964, in Querfurt. His career in media began in 1982, working as a disc jockey and video jockey for fourteen years. After leaving this profession in 1996, he transitioned to working as a commercial spokesperson before beginning formal training as a voice actor in 2000, which he completed successfully in 2001. Since 1996, he has worked as a freelance speaker and voice actor in Berlin.

Hassert is most widely recognized by German audiences as the definitive voice of Professor Hershel Layton. He first voiced the character in the six main video games of the Professor Layton series. He reprised this role for the animated film Professor Layton and the Eternal Diva, providing the German voice for the protagonist. His association with the character continued years later for the anime television series Layton Mystery Tanteisha: Katori no Nazotoki File, where he again voiced the character of Hershel Layton.

Beyond the Layton franchise, Hassert has an extensive body of work in video games and animation. Some of his notable video game roles include Frank Woods in the Call of Duty: Black Ops series, Thrall in World of Warcraft and Heroes of the Storm, Viktor Vektor in Cyberpunk 2077, and the character Daud in Dishonored 2. In the Sonic the Hedgehog franchise, he voiced the characters Infinite and E-123 Omega for the game Sonic Forces. His work also extends to dubbing live-action actors for the German market, with a list of recurring voices including actors such as James Arnold Taylor, Liev Schreiber, and Kyle MacLachlan.

In addition to character work, Hassert is a prominent off-screen narrator for documentaries and reportage, having been the off-speaker for the RTL II program EXKLUSIV - Die Reportage since 2002. He has also served as the station voice for several major German television channels, including Sat.1 until 2010 and Rundfunk Berlin-Brandenburg (rbb) from November 2010 onward. His career also includes work as a singer and occasional on-screen acting roles in German television series such as Praxis Bülowbogen and Gute Zeiten, schlechte Zeiten.