James Joseph "Gene" Tunney (May 25, 1897 – November 7, 1978) was an American professional boxer and the World Heavyweight Champion from 1926-1928 who defeated Jack Dempsey twice, first in 1926 and then in 1927. Tunney's successful title defense against Dempsey is one of the most famous bouts in boxing history and is known as The Long Count Fight. Tunney retired as an undefeated heavyweight after his victory over Tom Heeney in 1928.

Mary Lydon from Culleen House, Gorthgarve, Kiltimagh, Ireland, emigrated to the United States after the Great Famine. She settled in New York City where she met John Tunney, also from Cill Aodain, Kiltimagh, County Mayo, Ireland. They married after a short courtship. The Tunneys had seven children; one son was killed in a homicide around 1920, another was a NYPD Detective from 1924 to 1951, dying in 1971, while Gene would become famous as a World Heavyweight Boxing Champion. Tunney fought some 68 official professional fights, losing only one, to Harry Greb, while fighting as a light heavyweight. He reported that he lost a second fight during World War I, a 10 round decision, to Tommy Loughran, as a Marine before he began his professional boxing career. Tunney was regarded as an extremely skillful boxer who excelled in defense. In addition to beating Dempsey, the most famous fighter of his era, Tunney defeated Tommy Gibbons, Georges Carpentier and many other fine boxers.

James John "Gentleman Jim" Corbett (September 1, 1866 – February 18, 1933) was an American professional boxer and a former World Heavyweight Champion, best known as the man who defeated the great John L. Sullivan. He also coached boxing at the Olympic Club in San Francisco. He stood at 6 ft 1 in (1.85 m), with a reach of 73 inches (185 cm).

Dubbed by the media as "Gentleman Jim Corbett," he graduated from Sacred Heart High School in San Francisco and was rumored to have a college education. He also pursued a career in acting, performing at a variety of theatres. He has been called the "Father of Modern Boxing" because of his scientific approach and innovations in technique.^{[citation needed]} Some think that he changed prizefighting from a brawl to an art form.^{[citation needed]}

On May 21, 1891, Corbett fought Peter "Black Prince" Jackson, a much-heralded bout between cross-town rivals, since Corbett and Jackson were boxing instructors at San Francisco's two most prestigious athletic clubs. They fought to a no contest after 61 rounds.

William Harrison "Jack" Dempsey ("The Manassa Mauler") (June 24, 1895 – May 31, 1983) was an American professional boxer who held the World Heavyweight Championship from 1919 to 1926. Dempsey's aggressive style and exceptional punching power made him one of the most popular boxers in history. Many of his fights set financial and attendance records, including the first million dollar gate. He is listed #10 on The Ring's list of all-time heavyweights and #7 among its Top 100 Greatest Punchers. In 1950, the Associated Press voted Dempsey as the greatest fighter of the past 50 years. He is a member of the International Boxing Hall of Fame.

Born in Manassa, Colorado, with the name of William Harrison Dempsey, he grew up in Colorado, West Virginia and Utah, in a poor family of mixed ancestry. His father, Hiram Dempsey, was of Irish, Cherokee descent and his mother, Mary Celia (née Smoot), was also of Irish and Cherokee descent. Both parents became Mormon converts, and Jack was baptized on August 2, 1903, after he reached the required age of accountability. Jack would later write, "I'm proud to be a Mormon. And ashamed to be the Jack Mormon that I am." Because his father had difficulty finding work, the family traveled often. He dropped out of grade school to work. Dempsey left home at the age of 16, eager to start a better life for himself. Due to lack of money, he frequently had to travel underneath trains and sleep in hobo camps. However, Dempsey was a strong, powerful youth who soon discovered a talent for fighting. With the help of his older brother Bernie, he commenced training as a professional boxer. In 1927, tragedy befell Dempsey's family when his other brother, John, shot his own wife, then killed himself in a murder-suicide.

Georges Carpentier (pronounced car-pont-yay) (January 12, 1894 – October 28, 1975) was a French boxer. He fought mainly as a light heavyweight and heavyweight in a career lasting from 1908-26. Nicknamed the "Orchid Man", he stood 5 feet 11+¹⁄₂ inches (1.82 m) and his fighting weight ranged from 125 to 175 pounds (57 to 79 kg). Carpentier was known for his speed, his excellent boxing skills and his extremely hard punch.

Born in Liévin near Lens, Pas-de-Calais, Carpentier began his career by progressing up through the weight divisions, fighting in every division from welterweight upwards. With his first professional bout at age 14, he was welterweight champion of France and of Europe in 1911, middleweight champion of Europe in 1912, and light heavyweight champion of Europe in 1913. On June 1, 1913, he beat "Bombardier" Billy Wells in Ghent, Belgium to become heavyweight champion of Europe. He defended his title in December against Wells, in January 1914 against Pat O'Keefe and in London on July 16 he beat Ed "Gunboat" Smith to add the "White Heavyweight Champion of the World" to his European title. Carpentier was also a referee during the early stages of his career, supervising a number of fights including the world title bout between Jack Johnson and Frank Moran in June 1914. Carpentier was an aviator during World War I and was awarded two of the highest French military honors, the Croix de Guerre and the Médaille Militaire. This served to heighten his already phenomenal popularity, not only in France but in the United States and England as well.

Thomas Heeney (18 May 1898 – 15 June 1984), commonly known as Tommy gun Heeney, was a professional heavyweight boxer from New Zealand, best known for unsuccessfully challenging champion Gene Tunney for the heavyweight championship of the world in New York City on 26 July 1928.

Heeney was born in Gisborne, New Zealand, and worked as a plumber until he left New Zealand. He was a strong swimmer and was awarded a bronze medal by the Royal Humane Society of New Zealand in 1918 for helping rescue two women from the sea off Waikanae Beach, Gisborne. He also retrieved a third woman who did not survive.

He learnt to box from his father and his older brother Jack Heeney, who was the New Zealand amateur welterweight champion in 1914 and middleweight champion from 1919 to 1924. He became a professional boxer when he fought Bill Bartlett in Gisborne in 1920. In October 1920, Heeney became the New Zealand heavyweight champion when he beat Brian McCleary of Dunedin on a technical knockout. Heeney was also a rugby union player and played for the Hawke's Bay — Poverty Bay team against the Springboks in 1921. He boxed in Australia and won the Australian heavyweight champion title in 1922, and fought in England and South Africa in 1924.