ONE Championship is home to some of the most elite athletes in the world, with some of them proving it in multiple sports or weight classes.Claiming a title is part of the goals of any martial artist as it is a testament to the skills they worked hard to develop. While weight classes are made to level the playing field, some of the most legendary fighters have conquered different divisions to prove that they are good, no matter the circumstances that are against them. Boxing greats like Roy Jones Jr., 'Sugar' Ray Leonard, Oscar De La Hoya, Floyd Mayweather, and Manny Pacquiao are just a few names that come to mind.In ONE Championship, athletes are able to test themselves in multiple disciplines apart from migrating to a different weight class. As such, fighters can test themselves against world champions in MMA, Muay Thai, and kickboxing, all in different weight classes.ONE 159 main event fighter Reinier de Ridder is one of the few two-division world champions in the promotion, and he will put one of them on the line when Vitaly Bigdash challenges him for the ONE middleweight world title. View this post on Instagram Instagram PostMeanwhile, co-main event star Janet Todd is looking to become a two-sport world champion when she takes to the circle on July 22. The American is set to take on promotional newcomer Lara Fernandez for the ONE interim atomweight Muay Thai world title.Here are the other world champions who have held two golds on their shoulders.#5. Martin Nguyen - ONE Championship’s first two-division world championAfter splitting his first two assignments in ONE Championship, Martin Nguyen racked up four straight first-round victories in the circle to earn a second shot at Marat Gafurov’s ONE featherweight world title in 2017.He made the most out of his opportunity by knocking out the Dagestani in the second round of their matchup. After dominating the competition in the featherweight ranks, Nguyen decided to move up and challenge the next division's champion, Eduard Folayang.After just three months, ‘The Situ-Asian’ found himself in Manila, standing across the hometown hero and ONE lightweight world champion Folayang. By the second round, Nguyen found an opening to unleash a devastating overhand right to end the contest and shock the world. View this post on Instagram Instagram PostThe feat gave Nguyen the distinction of being the first double-world champion in ONE Championship.