John or Jack Kelly may refer to:

People

Academics and scientists

• John Kelly (engineer), Irish professor, former Registrar of University College Dublin
• John Kelly (scholar) (1750–1809), at Douglas, Isle of Man
• John Forrest Kelly (1859–1922), scientist
• John Larry Kelly Jr. (1923–1965), scientist at Bell Labs
• John F. Kelly (professor), professor of addiction medicine
• John Norman Davidson Kelly, British theologian and academic

Arts and entertainment

• Jack Kelly (actor) (1927–1992), American film and TV actor, in U.S. TV series Maverick
• John Kelly (actor) (1901–1947), American film actor whose credits include Meet Dr. Christian
• John Kelly (artist) (born 1965), Australian artist
• John Kelly (author) (born 1964), British author and illustrator
• John Kelly (born 1978), member of the Doctor Who Restoration Team
• John Kelly (Irish broadcaster) (born 1965), Irish radio broadcaster and presenter of The View
• John Liddell Kelly (1850–1925), British journalist and poet
• John Melville Kelly (1879–1962), American/Hawaiian artist
• John Kelly (performance artist) (born 1959), American performance artist, visual artist and writer
• Johnny Kelly (born 1968), American drummer

Politicians

United Kingdom

• John Kelly (Sinn Féin politician) (1936–2007), Northern Irish republican leader
• John Richards Kelly (1844–1922), British Member of Parliament for Camberwell North, 1886–1892
• Basil Kelly (John William Basil Kelly, 1920–2008), Northern Irish Unionist politician

United States

• Jack Kelly (politician) (born c. 1939), former Philadelphia Republican councilman-at-large
• John Kelly (New York politician) (1822–1886), politician in Tammany Hall, U.S. Representative from New York (1855–1858)
• John B. Kelly (Boston politician) (died 1969), Boston City councilor
• John David Kelly (1934–1998), American judge
• John F. Kelly (born 1950), former White House Chief of Staff, United States Marine Corps general, and Secretary of Homeland Security
• John F. Kelly (Michigan politician) (1949–2018), Judge Advocate General and State Senator for Michigan
• John R. Kelly (born 1946), Republican member of the West Virginia House of Delegates
• John V. Kelly (1926–2009), American Republican Party politician in New Jersey
• John Kelly (Brooklyn politician) (1855–1900), American politician from New York

Other countries

• John Kelly (bailiff) (c. 1793–1854), Member of the House of Keys and High Bailiff of Castletown, Isle of Man
• John Kelly (Canadian politician) (1852–1934), municipal councillor in Edmonton, Alberta, Canada
• John Kelly (New South Wales politician) (1840–1896), Australian politician
• John Kelly (Roscommon politician) (born 1960), Irish Labour Party Senator
• John M. Kelly (politician) (1931–1991), Irish Fine Gael politician, cabinet member, legal scholar, and novelist
• John Robert Kelly (1849–1919), farmer and politician in colonial South Australia

Military personnel

• John Kelly of Killanne (died 1798), leader of the Irish Rebellion of 1798 in Wexford
• Jack Sherwood Kelly (1880–1931), adventurer and soldier awarded the Victoria Cross
• John Kelly (Royal Navy officer) (1871–1936), British Admiral of the Fleet
• John D. Kelly (Korean War soldier) (1928–1952), USMC, Korean War Medal of Honor recipient
• John D. Kelly (World War II soldier) (1923–1944), American soldier, World War II Medal of Honor recipient
• John F. Kelly (born 1950), White House Chief of Staff, United States Marine Corps general, and Secretary of Homeland Security
• John H. Kelly (1840–1864), Confederate brigadier general
• John J. Kelly (1898–1957), USMC, World War I, Army Medal of Honor and Navy Medal of Honor recipient

Sportspeople

Association football

• Jack Kelly (English footballer) (1913–2000), English footballer with clubs including Burnley and Leeds United
• John Kelly (footballer, born 1909) (1909–?), English footballer for York City
• John Kelly (footballer, born 1913) (1913–?), English footballer for Bradford City
• John Kelly (footballer, born 1921) (1921–2001), Scottish international football player (Barnsley)
• John Kelly (footballer, born 1935), Scottish footballer for Crewe Alexandra
• John Kelly (footballer, born 1960), Anglo-Irish soccer player whose clubs included Tranmere Rovers, Preston
• John Paul Kelly (football) (born 1987), Irish footballer

American football

• John Kelly (offensive lineman) (born 1944), American football player
• John Kelly (running back) (born 1996), American football running back
• Shipwreck Kelly (American football) (John Simms Kelly, 1910–1986), American football player

Rugby football

• John Kelly (rugby, born 1917), English former rugby union and professional rugby league footballer
• John Kelly (rugby union, born 1974), Irish rugby union player
• Jack Kelly (rugby union, born 1926) (1926–2002), New Zealand rugby union player
• Jack Kelly (rugby union, born 1997), Irish rugby union player

Other sports

• Kick Kelly (John O. Kelly, 1856–1926), American baseball player and umpire, boxing referee and gambling operator
• Jack Kelly (Australian footballer) (1916–1971), Australian rules footballer for St Kilda
• John Kelly (boxer) (1932–2016), Northern Irish boxer
• John Kelly (catcher) (1859–1908), 1879–1884 baseball player
• John Kelly (equestrian) (born 1930), Australian Olympic equestrian
• John Kelly (golfer) (born 1984), American amateur golfer
• John Kelly (Lancashire and Derbyshire cricketer) (1922–1979), English cricketer
• John Kelly (Nottinghamshire cricketer) (1930–2008), English cricketer
• John Kelly (outfielder) (1879–1944), 1907 baseball player
• John Kelly (racewalker) (1929–2012), Irish Olympic athlete
• John Kelly (sportscaster) (born 1960), ice hockey sportscaster
• John Kelly (Tipperary hurler) (born 1948), Irish retired sportsperson
• Jack Kelly Jr. (rower) (1927–1985), John B. Kelly Jr., an Olympic rower, Philadelphia councilman, head of the US Olympic Committee and brother of Grace Kelly
• Jack Kelly Sr. (rower) (1889–1960), John B. Kelly Jr. (nicknamed "Jack"), Olympic rower, father of actress, Grace Kelly and John B. Kelly Jr.
• Jack Kelly (hurler) (born 1996), Irish hurler
• John Kelly (runner) (born 1984), American endurance athlete
• John-Paul Kelly (ice hockey) (born 1959), Canadian ice hockey player

Other people

• John Kelly (1840–1904), British architect specialising in churches, see Kelly & Birchall
• John Kelly (diplomat) (born 1941), British diplomat and governor of the Turks and Caicos Islands
• John Kelly (minister) (1801–1876), Congregational minister
• John A. Kelly (1943–1978), American investigative journalist in Boston, Massachusetts
• John E. Kelly III, American executive at IBM
• John Gregory Kelly (born 1956), American Roman Catholic bishop
• John Hall Kelly (1879–1941), former Canadian High Commissioner to Ireland
• John Hubert Kelly (1939–2011), U.S. diplomat
• John P. Kelly (clergyman), convening apostle of the International Coalition of Apostolic Leaders

Characters

• Jack Kelly, character in the 1992 Disney film Newsies, played by Christian Bale, and the Disney stage musical Newsies where the role was originated by Jeremy Jordan
• Jack Kelly, lawyer uncle in It's Always Sunny in Philadelphia with concerns about the size of his hands
• John Clark (Ryanverse character), character in a number of Tom Clancy novels
• John Kelly (NYPD Blue), character on the TV series NYPD Blue, played by David Caruso
• John Kelly, character on the TV series Brooklyn Nine-Nine, played by Phil Reeves

Other

• John Kelly Girls' Technology College
• John P. Kelly (album), a 2001 album by rapper Mr. Cheeks