Henrietta "Hetty" Lange is the operations manager for the Naval Criminal Investigative Service's Office of Special Projects which is located in Los Angeles.
She appeared in the NCIS: Los Angeles Season 1 episode, Episode: Identity, replacing Lara Macy who had originally held the position but following an assassination attempt on G. Callen, Macy was reassigned elsewhere before being murdered prior to the NCIS Season 7 episode, Patriot Down (episode), resulting in Hetty being given the position of Operations Manager which she holds to this day.
Despite her small size, Hetty is by no means a pushover and is something of an intimidating figure. She often uses her resources to ensure that the safety of her Agents and she's also a fan of Lady Gaga.
After Agent Dominic Vail died in the line of duty, Hetty attempted to resign from her position as Operations Manager but stayed on despite having taken Vail's death very hard.