Mitnick, Mitnik, Mytnik, or Mytnyk is a surname of Slavic-language origin, signifying a toll collector. Mytnik is the Polish, Belarusian (Belarusian: Мытнік), and Russian (Russian: Мытник) form. Its Ukrainian version is Mytnyk (Ukrainian: Митник). The surname may refer to:
- Kevin Mitnick (born 1963), American computer security consultant, author and hacker
- Tadeusz Mytnik (born 1949), Polish cyclist.
- Vadzim Mytnik (born 1988), Belarusian association football player
- "Mitnick". ancestry.com. Retrieved March 4, 2017.