Mary Lou, Mary-Lou, Marylou or Marilou may refer to:

People

• Marilou (singer) (Marilou Bourdon, born 1990), French-Canadian pop singer and cookbook author
• Marilou Awiakta (born 1936), American poet
• Mary Lou Belli (fl. 1984–present), American television director and author
• Marilou Berry (born 1983), French actress, film director and screenwriter
• Mary Lou Beschorner (1929–2008), American player in the All-American Girls Professional Baseball League
• Mary Lou Clements-Mann (1946–1998), American biologist
• Mary Lou Crocker (1944–2016), American golfer
• Mary-Lou Daniels (born 1961), American retired tennis player
• Marylou Dawes (1933–2013), Canadian concert pianist
• Marilou Diaz-Abaya (1955–2012), Filipino film director
• Mary Lou Dickerson (born 1946), American politician
• Marilou Dozois-Prévost (born 1986), Canadian weightlifter
• Mary Lou Fallis (born 1948), Canadian opera singer
• Mary Lou Farrell (1942–2011), Canadian singer, actress and beauty queen
• Mary Lou Finlay (born 1947), Canadian radio and television journalist
• Mary Lou Forbes (1926–2009), American Pulitzer Prize-winning journalist and commentator
• Mary Lou Foy (born 1944), American photojournalist
• Mary Lou Freeman (1941–2006), American politician
• Mary Lou Goertzen (1929–2020), American artist, peace activist and Mennonite
• Mary Lou Graham (born 1936), American player in the All-American Girls Professional Baseball League
• Mary Lou Jepsen (born 1965), American entrepreneur, business executive and inventor
• Mary Lou Kolbenschlag (born 1992), American actress - see Mary Lou (actress)
• Mary Lou Lord (born 1965), American indie folk musician and busker
• Mary Lou Makepeace (born 1940, American politician
• Mary Lou McDonald (born 1969), Irish politician, leader of the Sinn Féin party
• Mary L. McMaster, American oncologist and clinical trialist
• Mary Lou Metzger (born 1950), American singer and dancer
• Mary Lou Munts (1924–2013), American politician and lawyer
• Mary Lou Petty (1915–2014), American swimmer
• Mary Lou Rath (fl. 1978–present), American politician
• Mary Lou Retton (born 1968), American retired gymnast, 1984 Olympic all-around champion
• Mary Lou Robinson (1926–2019), American federal judge
• Mary Lou Soffa, American computer scientist
• Mary Lou Studnicka (1931–2014), American pitcher in the All-American Girls Professional Baseball League
• Mary Lou Turner (born 1947), American country music singer
• Mary Louise Marylou Whitney (1925–2019), American philanthropist and socialite
• Mary Lou Williams (1910–1981), American jazz pianist, arranger and composer
• Mary Lou Zoback (born 1952), American geophysicist

Fictional characters

• Mary Lou Collins, in The Larry Sanders Show
• Marylou, a character in the novel On the Road by American writer Jack Kerouac
• Marylou Ahearn, a character in the novel The Revenge of the Radioactive Lady by Elizabeth Stuckey-French
• Marylou, a character in the movie The Howling (film) played by Elizabeth Shé