The SIG-Sauer P228 is a pistol.
JAG
In the JAG Season 8 episode, Meltdown (episode) which was also a backdoor pilot episode for the first spin-off series, NCIS, the three members of the main NCIS Major Case Response Team, NCIS Special Agents Leroy Jethro Gibbs, Anthony DiNozzo and Vivian Blackadder were all seen carrying SIG-Sauer P228's as their personal sidearms.
NCIS
It is the standard issued sidearm of members of the NCIS Major Case Response Team as well as other agents associated with the NCIS agency.
In NCIS Season 1, Gibbs, DiNozzo and new NCIS recruit Caitlin Todd were all seen carrying SIG-Sauer P228s as their respective sidearms.
In Yankee White (episode), Caitlin Todd tells Gibbs he can't bring his SIG-Sauer on Air Force 1, if he was going to tag along. He obtains a SIG-Sauer from Air Force Q's armory to take down Leonard Rish, who took a Heckler & Koch MP5K from it to kill President Bush.
In the NCIS Season 1 episode, Minimum Security (episode), NCIS Special Agent Paula Cassidy was seen holding and even using her own SIG-Sauer P228.
In the NCIS Season 1 episode, Bête Noire (episode), terrorist Ari Haswari was seen holding Kate Todd's SIG-Sauer during the NCIS Hostage Crisis.
In NCIS Season 2, Gibbs, DiNozzo, Kate and new team member Timothy McGee were all seen carrying or using their SIG-Sauer P228s.
In NCIS Season 3, Mossad Liaison Officer Ziva David and NCIS Director Jenny Shepard were both seen carrying SIG-Sauer P228s.
In NCIS Season 4, FBI agent Tobias Fornell and his colleague, Ron Sacks were seen with SIG-Sauer P228s.
In the NCIS Season 6 episode, Legend (Part 1) (episode) and Legend (Part 2) (episode), the NCIS agents assigned to the Office of Special Projects in Los Angeles were revealed to be carrying the SIG-Sauer P228 with G. Callen, Sam Hanna and Kensi Blye all wielding the guns.
Ziva David's SIG-Sauer P228. From the NCIS Season 9 episode, "Housekeeping".
In NCIS Season 9, it continues to be the main firearm used by NCIS agents.
CGIS agent Abigail Borin produces a SIG-Sauer P228 during the NCIS Season 9 episode, Safe Harbor (episode) while the NCIS Season 9 episode Rekindled (episode), Baltimore Detective Jason King draws a SIG-Sauer P228.
In NCIS Season 10, it is seen being wielded or used many times by the agents from the NCIS Major Case Response Team.
It appeared in many episodes of NCIS Season 11, being the personal sidearm for members of the NCIS MCRT and it appears to be the main weapon of choice for the NCIS agents who work in the NCIS: New Orleans office.
It appeared in many episodes of NCIS Season 12 and 13 as the personal sidearm for members of the NCIS MCRT.
In NCIS Season 14, it is the personal sidearm for members of the NCIS MCRT with the exception of Nicholas Torres who wields a Heckler & Koch P2000SK. NCIS agent Alexandra Quinn is seen wielding a SIG-Sauer P228 for the first time in the episode, Philly (episode).
In NCIS Season 15, in addition to Gibbs and McGee using it, the SIG-Sauer P228 appeared during the episodes, House Divided (episode) and Exit Strategy (NCIS episode).
In NCIS Season 16, McGee continues using the SIG-Sauer P228.
In NCIS Seasons 17 and 18, McGee is the only member of the NCIS MCRT to continue using the SIG-Sauer P228 as his fellow NCIS colleagues have switched to other sidearms.
In NCIS Season 19, McGee and Jessica Knight use the SIG-Sauer P228 as their sidearms.
NCIS: Los Angeles
In NCIS: Los Angeles Season 1, all the agents assigned to OSP are seen using the SIG-Sauer P228 as their main sidearm. It appeared in the NCIS: Los Angeles Season 1 premiere episode, Identity (episode) with Luis Perez being seen holding a custom SIG-Sauer P228.
In NCIS: Los Angeles Season 2, the NCIS agents who are also members of OSP are regularly seen using their SIG-Sauer P228s.
In the NCIS: Los Angeles Season 2 episode, Borderline (episode), Psychologist Nate Getz is seen at the OSP Shooting Range, practicing his marksmanship by shooting targets while using a SIG-Sauer P228.
In the NCIS: Los Angeles Season 2 episode, Absolution (episode), two DGSE agents pull their respective SIG-Sauer P228s on both Kensi and Deeks.
By NCIS: Los Angeles Season 3, Callen, Sam and Kensi have all begun using the SIG-Sauer P229 E2.
In NCIS: Los Angeles Season 4, Nate Getz was shown wielding a SIG-Sauer P228. He is the only member of the NCIS: Los Angeles to carry the weapon as his colleagues who previously used the sidearm have all switched to the SIG-Sauer P229 E2.
NCIS: New Orleans
Members of the NCIS team in New Orleans also carry the SIG-Sauer P228 as their sidearms, prime examples being NCIS agents Dwayne Pride and Christopher LaSalle.
The weapon appeared in the NCIS: New Orleans Season 2 episodes, Insane in the Membrane (episode) and Means to an End (episode).
It appeared in the NCIS: New Orleans Season 3 episode, Hell on the High Water (episode).
It appeared in various episodes of NCIS: New Orleans Season 4.
It also appeared in numerous episodes of NCIS: New Orleans Season 5.
In episodes of NCIS: New Orleans Season 6, the SIG-Sauer P228 was seen being wielded by agents from the DIA- Defense Intelligence Agency and later by NCIS agent Quentin Carter who uses one as his personal sidearm.
However, in NCIS: New Orleans Season 7, it was shown that Pride, Sebastian and Carter had stopped using their SIG-Sauer P228s and replaced them with the SIG-Sauer P229 E2, the same weapon their counterparts at the OSP in Los Angeles currently use.
NCIS: Sydney
It appeared in the NCIS: Sydney Season 1 series premiere episode, Gone Fission (episode).