When the heavyweight division is booming, there really is no division like it.
Older than American Football, MLB and soccer, boxing is the oldest form of sport with it going back to the 12th Century where people would go toe-to-toe in bare knuckle fights.
John L. Sullivan won boxing's first lineal title in 1885 and made the first defence of his belt four years later against James J. Corbett, who then became the first man to defeat the legendary Sullivan.
Knockout artist Bob Fitzsimmons is Britain's first heavyweight world champion. He ousted Corbett in 1897 and became the first boxer in history to win world titles in three divisions with the other two at middleweight and light heavyweight.
Elsewhere, Muhammad Ali is the only heavyweight to have won the lineal title on three occasions while Tyson Fury, Lennox Lewis, Floyd Patterson, Evander Holyfield and George Foreman have earned the status twice.
"Big George" is the oldest heavyweight world champion at the age of 45 while 'Iron' Mike Tyson is the youngest at 20. As it stands, Fury is the lineal champion and between him and unified king Oleksandr Usyk - they own the heavyweight division with the WBA, WBC, IBF, WBO, Ring Magazine and lineal straps.
To celebrate boxing's most popular division - after Fury made a second successful defence of his title against Dillian Whyte - Planet Sport takes a look at the five best heavyweights of all-time. If you disagree, tweet us your top five @planetsportcom.
5) Rocky Marciano
'The Rock from Brockton' is the only heavyweight champion to have retired with an undefeated record at 49-0. Not only is his record on paper unrivalled, but he also possesses one of the most impressive knockout ratios in history with 87%.
Rocky started his career just a couple of years after World War Two and reached the pinnacle in 1952 by beating Jersey Joe Walcott.
Rocky then made six successful defences, including a first-round KO against Walcott and two wins over Ezzard Charles. His 49-0 record - which ended with a win over Archie Moore - was finally beaten in 2017 when Floyd Mayweather defeated Conor McGregor to go 50-0.
4) Jack Dempsey
William Harrison 'Jack' Dempsey - known as the "Manassa Mauler" - had a seven-year reign as heavyweight champion between 1919 to 1926. It was a glorious time to be a New Yorker with Dempsey and the Yankees dominating sport.
In the '20s, Dempsey was seen as the man who got boxing on the map with his exceptional punching style and ability to showcase his aggressive style.
His popularity attracted the first million-dollar gate. In 1919, Dempsey won the lineal strap with a destructive victory over Jess Willard. It was a three-round demolition that saw Willard knocked down SEVEN times in the opening round.
As a result of the brutal beatdown, his opponent left the ring with fewer teeth, several broken ribs and a fractured jaw.
There were accusations of Dempsey having a knuckle duster wrapped inside his gloves although Ring Magazine founder and editor Nat Fleischer, who was present at the time of his hands being wrapped, denied such claims.
3) Jack Johnson
Johnson is the first African American fighter to have won the heavyweight title in 1908 and held the title for seven years before surrendering it in 1915 to Willard. He is highly regarded as one of the most dominant heavyweight champions in history.
Dealing with racism and discrimination his whole life, Johnson is celebrated among society as the man who paved the way for a new generation of black fighters in the sport. Johnson's record is 72-11-11 (3).
His most famous victory was in front of 20,000 fans in the 'Fight of the Century' against James J. Jeffries in 1910. He would continue to fight until the ripe age of 60 before retiring after seven defeats in nine fights.
More than 100 years after being convicted for violating the Mann Act, President Donald Trump granted a full pardon to Johnson in 2018.
2) Joe Louis
"Everyone has a plan until they've been hit" is a famous boxing observation from Joe Louis.
Following on from Dempsey, Louis got boxing back into the mainstream and is one of the most inspiring athletes in sporting history having fought through WW2.
Starting his career in 1934, Louis would win his first heavyweight title in 1938 and made a record 25 defences - something which has never been beaten. A defining fight in his career is the rematch against Max Schmelling.
Seen as part of their Aryan race, Nazi officials flocked to New York with Schmelling promising the world their man would crush Louis. Schmelling had previously beaten Louis in 1936 via KO in round 12.
Before one of the biggest events of the 20th Century, president Franklin D. Roosevelt invited Louis to the White House and told him, "we need muscle like you to beat Germany."
The 'Brown Bomber' - the poster boy for inspiring men and women to sign up and protect America during WW2 - avenged his defeat to the German, blasting him out in less than three minutes inside the Yankee Stadium.
Louis retired as the champion in 1949 before making two comebacks. Louis would again hang the gloves up in 1951 with a 66-3 record after losing to Marciano.
1) Muhammad Ali
Muhammad Ali is the most famous sportsman of all-time. Originally named Cassius Clay, he would later be known as Muhammad Ali after converting to the faith of Islam. He was pivotal in protesting for African Americans during the civil rights movement and fought for equality around the globe.
Ali first made a name for himself at the 1960 Olympics in Rome after winning gold. It's believed Ali threw his medal into a river though after he and a friend got refused entry to a restaurant because of the colour of their skin.
'The Champ' became heavyweight champion after producing a stunning victory over Sonny Liston but got stripped of the title and suspended from the sport for three years (1967 to 1970) because of his decision to boycott the Vietnam War.
In what was considered a hugely controversial move at the time, Ali refused to represent his country and in return was charged and found guilty of draft evasion.
Once his ban was lifted in 1970, Joe Frazier would inflict the first defeat of Ali's career a year later in 'The Fight of the Century'. He avenged the loss in 1974 at Madison Square Garden.
His most famous fights were the 'Rumble in the Jungle' and 'Thrilla in Manila' against an up-and-coming Foreman and a trilogy with Frazier, respectively. An estimated audience of more than one billion people tuned in from around the globe to witness Ali getting his hand raised in both contests.
He is the only three-time lineal heavyweight champion and won Ring Magazine's Fighter of the Year six times. His showmanship inside the ring and cultural impact outside of it has seen him ranked as not only the greatest heavyweight of all-time but the greatest fighter.