Dennis McCarthy may refer to:

• Dennis McCarthy (scientist), American scientist
• Dennis McCarthy (composer) (born 1945), American composer
• Dennis McCarthy (New York politician) (1814–1886), United States congressman and acting lieutenant governor of New York
• Dennis McCarthy (radio presenter) (1933–1996), British radio presenter
• Denis Florence MacCarthy (1817–1882), Irish poet
• Dennis M. McCarthy (1945–2023), U.S. Marine Corps general
• Dennis McCarthy, shooting victim of Colin Ferguson