Thomas "Tom" Morrow was the former NCIS Director, a position he held during Ice Queen (episode) and Meltdown (episode) and also Season One and Season Two up until his resignation from NCIS for good which occurred during the Season 3 premiere episode, Kill Ari Part 1 (episode).
Following Morrow's resignation from NCIS to become deputy director at Homeland Security, he was replaced by Jennifer Shepard and in the aftermath of Shepard's death in the Season 5 finale episode, Judgment Day Part 1 (episode), Leon Vance became the NCIS Director.
Despite having moved on from NCIS, Morrow had in recent years been in involved in various investigations with NCIS that have brought him back into contact with his former NCIS colleagues, particularly NCIS Special Agent Leroy Jethro Gibbs.
Tragically, Morrow's life came to an end in April 2016 when he was shot dead by a sniper, making him the second NCIS Director to have been killed, the first being his successor, Jennifer Shepard.
JAG Season 8
NCIS Season 1
NCIS Season 2
NCIS Season 3
NCIS Season 8
NCIS Season 10
NCIS Season 11
NCIS Season 12
NCIS Season 13
Leroy Jethro Gibbs
For a more detailed list, see Thomas Morrow/List of Appearances.