Leon Vance, portrayed by Rocky Carroll, first appeared in the episode "Internal Affairs" as Assistant Director in Season 5. He is named Director after the death
of Jenny Shepard. It has been revealed in the episode "Knockout" that he was originally from Ohio, but grew up in Chicago where he trained to be
a boxer. In this episode, his wife stated that Vance attended the United States Naval Academy and was commissioned as a 2nd Lieutenant in the Marine Corps, but was forced to take a medical discharge before ever serving due to having undergone surgery to repair a detached retina suffered during his boxing career. However, at the end of the episode, Ducky reveals to Gibbs that Vance's close, childhood friend who had died just prior to the start of the episode also suffered a detached retina. In the course of this episode, Vance also revealed that it was this friend who decided that Vance should leave Chicago while the friend stayed behind. Vance said this despite his insistence to Gibbs that his friend was a Marine though there was no record of his friend's service in the military.
In 1991, just prior to joining NCIS, Vance was a student at the United States Naval War College in Rhode Island. His coursework at this time included Combat Philosophy and Advanced Cryptography. It was during his time at the War College that he begun to take an interest in black operations and even imagined one himself: Operation Frankenstein, which would later play a big part in the season 8 finale. NIS took an interest in him and he was hired for an operation by Special Agent Whitney Sharp for an operation in Amsterdam codenamed Trident. Vance was trained by Sharp and left after a six-week training course for Amsterdam where he met his handler, Riler McAllister. McAllister told him that the target of the operation was a Russian intelligence operative who was known to Vance only as the Russian. NIS believed that he was bribing sailors in return for intelligence. Vance later met Eli David, a promising agent of the Mossad, who told him that he knew of the operation and that the Russian would kill him. Later, Eli betrayed Vance to the Russian but it was revealed that it was so that he would try to kill Vance sooner so that he could kill him himself. Eli also told Vance that he had been chosen because he was expendable and that he wasn't someone who would be missed. Eli and Vance kill the Russian's hit team but the Russian manages to escape and Eli is unable to find him or who he was for that matter. Vance was credited for the elimination of the hit team and he started to rise swiftly through the ranks at NCIS. He kept believing along with Eli, that Amsterdam was not what it had
seemed and they came to the conclusion that there was a dirty agent in NCIS, the one who had really tipped off the Russian of Vance's mission. It was later
revealed that McAllister had masterminded the entire operation: being an expert in Russia, he had seen that the Soviet Union's collapse had laid attention away
from Russia and onto the Middle East. Knowing that new attention to a potential Russian threat would throw him in the spotlight for Director of NIS, he had
planned to have Vance killed by a Russian operative so as to show that Russia still posed a threat and so that he could satisfy his ambitions.
Notably, Vance took over for Jenny Shepard during her leave of absence between "Internal Affairs" and "Judgment Day," establishing himself as a formidable presence with Gibbs and his team. He and Gibbs clash during this span, prompting a cold war between them which ends with a détente between the two of them in "Agent Afloat" at the start of the sixth season; however, the two of them clash later on, as Gibbs feels he cannot fully trust Vance, though he cannot identify a specific reason why. Vance spearheads the investigation into Jenny Shepard's death, and is angered greatly when he is not kept in the loop by Gibbs and Mike Franks, who ultimately manipulate the situation to exonerate Shepard from her past failure, not what Vance had in mind. After Shepard's death, and possibly before, he lobbies the Secretary of the Navy hard to take over NCIS, as told in "Cloak," but in "Semper Fidelis" the Secretary of the Navy informs Gibbs of a major operation which will require Vance to serve as its head, and that NCIS and the Navy will need Gibbs and Vance to get along, to which Gibbs is not comfortable but
appreciates the situation. Things come to a head in "Aliyah," when Gibbs accuses Vance of selling out his team to Mossad Director Eli David, to which Vance
responds that Ziva was a plant, used to get Mossad a foothole in NCIS through Gibbs. After this, the two of them realize that circumstances will prove one of
them right. At the start of the seventh season, Vance approves Ziva's transfer to NCIS, proving that Gibbs was right, and Ziva was loyal to NCIS. Despite his
professional attitude towards Gibbs's team, he shows that he does care about them at least once when Alejandro Rivera threatens Abby in "Spider and The Fly".
He tells Alejandro to leave before he gets hurt and when Alejandro asks by who, he replies angrily: "By me."
Even after the events of "Aliyah," Vance has been shown to still be in official contact with Eli David in David's capacity as Director of Mossad. This is shown when he receives a text message on his phone from Eli which says only: "I found him". Vance also refuses to discuss an Eli-phone call with Gibbs, despite knowing how dangerous Eli is, and his precarious relationship with Gibbs and his team.
Upon being promoted to the director's position at the end of Season 5, Vance immediately goes to former Director Shepard's office, and is seen to shred a single mysterious document from his own personnel file. It is later revealed in season 6 ("Semper Fidelis") that the document was written by his supervising agent at the time. The Secretary of the Navy tells Gibbs that the file is a fabrication and that he thought all copies had been destroyed. It is further revealed in the season 8 episode, "Enemies Domestic", that the head of the San Diego field office, when Vance was assigned there, had begun creating a legend for Vance that incorporated fictitious information about Vance in order to backstop a deep cover assignment, including the false information that Vance had been a pilot and director of a field
Leon Vance has a wife, Jackie, and two children, a daughter, Kayla, and a son, Jared. He met his wife while attending a University of Maryland basketball game while Len Biaswas playing.
Vance is also a recurring character on the NCIS spin-off, NCIS Los Angeles.