ONE Championship: Dynasty of Heroes (also known as ONE Championship 55) was a mixed martial arts event held by ONE Championship on May 26, 2017 at the Singapore Indoor Stadium in Kallang, Singapore. Background This event featured two world title fight for the ONE Women's Atomweight Championship Angela Lee of Singapore makes the second defense of her title against top contender Istela Nunes of Brazil as ONE Championship: Dynasty of Heroes headliner, for the ONE Welterweight Championship ONE Welterweight World Champion Ben Askren defends his title against rising young Malaysian star Agilan Thani as co-main event.