Harold Smith may refer to:

• Harold Jacob Smith (1912–1970), American screenwriter
• Harold J. Smith (1912–1980), TV actor better known as Jay Silverheels
• Harold Smith (Twin Peaks), fictional television character

• Harold Smith (New Zealand politician) (1866–1936), New Zealand MP
• Harold Smith (British politician) (1876–1924), MP for Warrington, 1910–1922, and Liverpool Wavertree, 1922–1923
• Harold Gengoult Smith (1890–1983), Australian medical practitioner and Lord Mayor of Melbourne
• Harold D. Smith (1898–1947), American budget director during World War II
• Harold Palmer Smith Jr. (born 1935), assistant secretary of Defense

• Harold Hill Smith (1910–1994), American geneticist
• Harold Smith (scientist) (born 1954), founder and CEO of OyaGen

• Harold Smith (diver) (1909–1958), American diver and Olympic gold medalist
• Harold Smith (gridiron football) (born 1962), American football player
• Harold Smith (sprinter) (born 1893), American sprinter also known as Harold Carman, 2nd in the 220 yards at the 1915 USA Outdoor Track and Field Championships

• Harold Page Smith (1904–1993), United States Navy admiral
• J. Harold Smith (1910–2001), Southern Baptist evangelist
• Harold Smith (detective) (1926–2005), art detective

• Whatever Happened to Harold Smith?, a 1999 British film
• Hal Smith (disambiguation)