José Aldo da Silva Oliveira Júnior (Portuguese pronunciation: [ʒoˈzɛ ˈawdu]; born 9 September 1986), known as José Aldo, is a Brazilian former professional mixed martial artist who competed in the Bantamweight and Featherweight divisions of the Ultimate Fighting Championship (UFC), where he was the inaugural and longest-reigning UFC Featherweight Champion, becoming champion after the UFC/WEC merger. Aldo is also the former interim UFC Featherweight Champion. He formerly competed in World Extreme Cagefighting, where he was the fourth and final WEC Featherweight Champion. Aldo is considered to be one of the greatest mixed martial artists of all time, and is often regarded as one of the greatest featherweights of all time after defending his UFC title seven times and his WEC title twice.
After his first MMA defeat in November 2005, Aldo remained undefeated for over a decade, winning 18 straight fights until UFC 194 in December 2015, when he lost to Conor McGregor. He was named Sherdog's 2009 Fighter of the Year. In Sherdog's April 2017 pound-for-pound ranking, Aldo was called "the greatest featherweight in mixed martial arts history."