John Riel Casimero (born February 13, 1990 in Ormoc, Leyte, Philippines), more commonly known as Johnriel Casimero, is a Filipino professional boxer.
He is a three-weight world champion, having held the WBO bantamweight title since November 2019 and previously, the IBF junior-flyweight title from 2012 to 2013 and the IBF flyweight title in 2016, as well as the WBO interim junior-flyweight title from 2009 to 2010 and WBO interim bantamweight title in 2019.
Quadro Alas is Tagalog for four of a kind when translated, his moniker means Four Aces.
Casimero currently resides in barangay Guizo in Mandaue City, Cebu, where he trains and lives in the city's IPI Gym.