McMullen is a surname with predominantly Irish origins but also with some Scottish history. It derives from root forenames such as: Maolain, Maelan "Hillock" and Meallain "Pleasant". All of these forenames have over time evolved to the collateral "Son of Maolain", anglicised McMullen.

Notable people with the surname include:

• Catherine Cookson (1906–1998), English author who published in the United States under her maiden name Catherine McMullen
• Curtis T. McMullen (born 1958), American mathematician
• Darren McMullen (born 1982), Scottish-Australian television and radio personality
• James McMullen, (1833–1913), Canadian politician
• John McMullen (1832–1883), Irish-born, American Roman Catholic bishop
• Mal McMullen (1927–1995), American professional basketball player
• Michael McMullen, South Australian architect, designer of Marryatville, South Australia#The Acacias and many other notable buildings in Adelaide
• Nathan McMullen (born 1988), English stage and TV actor
• Neil C. McMullen (1913–1992), American politician
• Peter McMullen (born 1942), British mathematician
• Phil McMullen (born 1958), music critic from England, founder of both Ptolemaic Terrascope magazine and the Terrastock festivals
• Ramsey MacMullen (1928–2022), American historian and writer
• Richard C. McMullen (1849–1926), American manufacturer and politician, Governor of Delaware
• Sean McMullen (born 1948), Australian science fiction writer
• Scott McMullen (born 1980), American football player
• Eugene McMullen (born 1958) Grew largest pumpkin in State of Illinois 2150 pounds, at time of weigh in the largest pumpkin ever grown in North America

See also

• McMullens, British regional brewery in Hertford, England
• McMullen Bros Ltd, Irish distributors of Maxol and Calor Gas fuel products
• Mac Maoláin, an Irish Gaelic surname