Nicolas Fiorello Amaro, Jr. is a fictional character on the NBC police procedural drama Law & Order: Special Victims Unit, portrayed by Danny Pino.

He also has a son with a former lover, Cynthia Mancheno (Andrea Navedo), named Gil (Jaden Matthew Rodriguez), whom he meets for the first time in the episode "Undercover Blue".

Amaro is an NYPD detective 2nd grade who transfers to the Special Victims Unit after spending time with both the warrants and narcotics squads.

This, along with his erratic behavior, briefly alienates his SVU colleagues; for example, they are reluctant to give him sensitive information regarding the false charges against Captain Donald Cragen (Dann Florek), fearing that he will make matters worse.

[12][13] In "Twenty-Five Acts", Amaro asks temporary SVU commanding officer Captain Steven Harris (Adam Baldwin) to let him work their rape case solo, telling Benson she needs a partner she can trust.

[14] In the episode "Undercover Blue", Cassidy is put on trial for rape when he is falsely accused by a prostitute working for pimp Bart Ganzel (Peter Jacobson).

Sergeant John Munch (Richard Belzer) then informs him that the NYPD brass is requesting he take a paternity test because his ex-lover is claiming he has a son from the fling.

However, Benson tells him that, because of his history of misconduct accusations, the NYPD will never promote him no matter how well he does; angered, Amaro throws his study materials in the garbage but he eventually gets over it.

Shortly thereafter, Amaro is involved in a courtroom shootout with Johnny Drake (Charles Halford), a brutal sex trafficker and pimp.

Before Amaro leaves, Benson remarks on how much her life has changed over the years of working with him and they make a promise to each other to stay friends forever.

[18] At the beginning of Season 17, Rollins mentions that Amaro is now living in Los Angeles, undergoing physical therapy for his injuries, and angling for a position with the United States Park Police.

[19] In the 500th episode, which aired during the 23rd season, Amaro is now a Genetics and Forensic Science graduate degree holder working for a company that specializes in analyzing cold-case DNA with new technologies, which bring him back to Manhattan in order to clear a man who was wrongfully convicted in a 1996 case which involved the sexual assault and fatal strangulation of a teenage girl.