Mary McCarthy or Mary MacCarthy may refer to:

• Mary Downing (1815–1881), Irish poet born Mary McCarthy
• Mary Stanislaus MacCarthy (1849–1897), Irish poet and nun
• Mary MacCarthy (1882–1953), English writer and member of the Bloomsbury Group
• Mary Eunice McCarthy (1899–1969), American screenwriter, playwright, and journalist
• Mary McCarthy (author) (1912–1989), American novelist, critic, and memoirist
• Mary McCarthy (screenwriter), American, screenwriter for movies Theodora Goes Wild (1936) and Sister Kenny (1946)
• Mary McCarthy (fiction writer) (1951–2013), Irish novelist, teacher, book reviewer

• Mary McCarthy (activist) (1866–1933), New Zealand temperance advocate and teacher
• Mary McCarthy Gomez Cueto (1900–2009), wealthy Canadian expatriate who lived an impoverished life in Havana
• Mary McCarthy (police officer) (1903–1978), Australian police officer
• Mary McCarthy (CIA) (born 1945), former CIA employee accused of leaking information
• Mary Ann McCarthy (1834–1887), Irish orphan who fatally stabbed her husband