Rosalita "Rosa" Diaz is a main character in the sitcom Brooklyn Nine-Nine. Secretive, brave, incredibly dark and with a serious temper problem, Rosa does not divulge anything about herself and is incredibly proud about the anonymity that surrounds herself at the Nine-Nine. Despite this demeanor, she does look out for her friends best interests.
She is portrayed by Stephanie Beatriz.
"Pilot", We also meet Detective Rosa Diaz, a stoic and mysterious coworker.
"The Slump", Amy recruits Rosa and Gina for help when Holt asks her to run lead on the Junior Policeman Program for at-risk youth
"48 Hours", Charles judges a pie contest between Gina and Rosa
"Old School", Terry and Charles work with Rosa to help her appearance on the witness stand.
"Sal's Pizza", Amy gets jealous when she learns Rosa was asked to be the new police captain.
"Pontiac Bandit", Peralta and Rosa try to track down an infamous carjacker and thief, the Pontiac Bandit.
"The Ebony Falcon", Captain Holt orders Santiago and Diaz to research about a theft Gina suffered at her home.
"The Party", Rosa unleashes Gina onto a group of abnormal psychologists who find her fascinating.
"Full Boyle", Sergeant Jeffords pulls a drug case from Rosa and Amy and gives it to Scully and Hitchcock, because the ladies chose to dismiss a geeky, wannabe superhero named Super Dan (Nate Torrence) who nonetheless had useful information.
Rosa has a prickly personality to put it gently. She doesn't display a lot of emotion, other than anger, divulge about her past and rarely smiles, normally remaining very blank and expressionless. Many people in the Nine-Nine are actually afraid of her as she tends to be extremely dark as well quite sadistic. Examples prove this when she was asked to go to her "happy place" by Terry and Boyle during a court case and it was a cabin in the woods with her brutally killing a lawyer whom she was annoyed by. Aside from this Rosa has a very sarcastic and macabre sense of humour.
Details about her past are quite sketchy, mostly because she doesn't share easily. What is known however was she used to ba a star pupil at a ballet class until she quit. Even her best friend, Jake Perlata knows only three things about Rosa, one of them being she owns a shower. Despite seeming emotionless, Rosa does have outbursts, she has an anger problem and tends to be massively temperamental to her co-workers however aside from this she is quite emotionless
She also proves to be a natual-born leader and was able to successfully lead the Anti-Drug Task Force into bringing down an entire drug ring. Rosa does display happiness at times. She was clearly overjoyed when she discovered the Task Force was a success and had an emotional breakdown when she had broken up with her boyfriend.