Carlos Javier Rivera Masso (born June 13, 1969 in San Juan, Puerto Rico) is a Puerto Rican singer. Masso is a former member of Menudo, joining the band at the height of Menudo's worldwide fame. He replaced Rene Farrait and quickly became a fan favorite with his participation on the albums of Por Amor and Una Aventura Llamada Menudo, which was the soundtrack of Menudo's second movie and Masso's first with the group.
Masso began his life as a Menudo the very moment that one of Menudo's members of the group's "golden era," Farrait, left the group. However, Masso's presence helped extend the golden era an additional three years, and when he left the group in 1987, he was the last member of the group's golden years to leave. Masso was a member of Menudo during their most commercially successful period in the States, which included the group's highest-charting U.S. single, "Hold Me." Masso's bandmates included Xavier Serbia, Johnny Lozada, Ricky Melendez, Miguel Cancel, Ray Reyes, Roy Rosselló, Robby Rosa and Ricky Martin, among others. He came back to Menudo to complete a tour in Brazil, their 1987 Summer in the Streets tour, after Robby Rosa quit the group, to introduce new member Ruben Gomez and for their last tour in the Philippines when Ralphy Rodriguez was pulled out of the group by his parents late that year.
After he left the band, Masso moved to Mexico for a very long time, where he was in a few soap operas. He got married and had a family, and in 1998 joined Melendez, Farrait, Lozada, Reyes and Cancel in touring many of the places where they had acquired millions of fans as Menudos, with El Reencuentro.