Edwin "Chapo" Rosario Rivera (Spanish pronunciation: [ˈeðwin roˈsaɾjo]; March 15, 1963 – December 1, 1997) was a Puerto Rican professional boxer who competed from 1979 to 1997.

Rosario's older brother Papo became a professional boxer, beginning what looked like a promising career.

[1] His boxing manager and coach (trainer), Manny Siaca Sr., had noticed the younger Edwin Rosario's talent when the boy was 8 years old.

Chapo's brother Papo died unexpectedly, purportedly due to drugs, two years after his entry into professional boxing.

This led to talks of a title fight against World Boxing Council (WBC) lightweight champion Alexis Argüello, to be held in Miami.

But Argüello relinquished the title in order to move up in weight to challenge junior welterweight champion Aaron Pryor.

With Arguello moving divisions, Rosario was matched with Mexico's José Luis Ramírez on May 1, 1983 for the vacant WBC lightweight title.

Rosario injured his hand during the fight and needed surgery, for which the World Boxing Council gave him a dispensation.

On June 13, 1986, he met the world champion Hector 'Macho' Camacho at Madison Square Garden in New York.

Because of the closeness of that bout, the WBA gave Rosario a chance to challenge Livingstone Bramble, one of two other world lightweight champions (the other one being the International Boxing Federation's Jimmy Paul).

Rosario defended the WBA lightweight title against fellow Puerto Rican Juan Nazario with a knockout in eight in Chicago.

In Rosario's next defense, he faced WBC super featherweight title holder Julio César Chávez, on November 21, 1987, in Las Vegas.

After Chavez vacated the title in 1989, Rosario came back and won it again, beating Anthony Jones, a tough Kronk prospect for the championship.

Many celebrities and dignitaries attended his funeral, and a group of Puerto Rican world boxing champions were among the pallbearers.