Jessica Knight is an entirely new character to “NCIS,” but Katrina Law, who plays the former REACT special agent, has appeared in film and TV projects since the early 2000s. Her first big role came in 2007, when she appeared in "The Rookie: CTU," a series of short webisodes which exist within the "24" universe.
She then appeared in 15 episodes of Starz's short-lived "Spartacus," where she played a slave named Mira. Mira becomes a series regular in Season 2 and becomes Spartacus' lover, but their romance is short-lived, as Mira gets killed off in the season finale.
Law got her first taste of a crime procedural show when she became a series regular on CBS’ “Training Day.” Law portrayed Detective Rebecca Lee, one of the most loyal officers in the LAPD's Special Investigation Section, but the show ended after the death of Bill Paxton in 2017.
After “Training Day’s” unfortunate end, Law landed on another CBS show, “Hawaii Five-0,” where she played another loyal team member, Quinn Liu. Her character quickly took on an active role in the task force's investigations and became an integral team member.
Arguably, her most memorable role before she landed on “NCIS” was Nyssa al Ghul on The CW's "Arrow," who was one of many LGBTQ+ characters to appear on the show. She appeared in 20 episodes and later reprised her role in a 2016 episode of "DC's Legends of Tomorrow."