Horwitz is a surname, and may refer to:
- People
- Bernhard Horwitz, chess player
- Brian Horwitz, American major league baseball outfielder
- Harry Moses Horwitz, aka Moe Howard, of the Three Stooges
- Jerome Lester Horwitz, aka Curly Howard, of the Three Stooges
- Maksymilian Horwitz, aka Henryk Walecki (1877–1937), leader and theoretician of the Polish communist movement
- Morton Horwitz (born 1938), legal historian and law professor
- Samuel Horwitz, aka Shemp Howard of the Three Stooges
- Steven Horwitz, American economist
- Tony Horwitz
- William Horwitz, Scientist Emeritus, formerly an analytical chemist at the Food and Drug Administration, USA
- Yosef Yozel Horwitz, rabbi
- Companies
- Horwitz Publishing House, Australian publisher of popular and pulp fiction, established in NSW in 1921
- Prize
- Louisa Gross Horwitz Prize