Owen Granger is one of the Assistant Directors of NCIS, a position below the Deputy Director of NCIS, a position held by Jerome Craig.
He first appeared in "The Watchers" where he questioned Hetty's ability to lead the OSP team and has been a recurring character ever since then.
He revealed at the end of "Crimeleon" he had arrived in Los Angeles to catch a killer which also showed him glancing out at Kensi who was in the shooting range, suggesting that he might be involved in the investigation of her father's death.
It was revealed in the episode, "Blye, K., Part 2" that he had also belonged to the same sniper unit that Kensi's father, Donald had been a member of.
Despite the team's misgivings or bad feelings about him, Granger helped the team track down the real killer, Peter Clairmont. He also shot Clairmont when the other man attempted to kill Kensi in revenge for her having beaten him in hand-to-hand combat.
As a result, Granger was assigned to stay in Los Angeles on a temporary basis and in the Season 3 finale, helped the team tackle the case of "The Chameleon", a serial killer responsible for the deaths of Agent Mike Renko and former Operations Manager Lauren Hunter.