U.S. Navy SEALs/Modern Warfare

Call of Duty 4: Modern Warfare
SEAL Team Six is mentioned in the level "Shock and Awe", where they assisted the NEST team in the failed attempt trying to disarm Al-Asad's nuclear device when Jackson and their team went to the LZ.

Campaign
The Navy SEALs make a couple appearances in the campaign of Modern Warfare 2. Unlike the other two friendly factions, the U.S. Army Rangers and Task Force 141, the player does not take the role of a member of the Navy SEALs.

During the level "Of Their Own Accord", they can be seen fast-roping down to the Dept of Commerce, and later taking off from the Department of Commerce in a Little Bird helicopter. During the attack on the Russian forces around the World War II Memorial, the helicopters carrying the SEALs are shot down.

SEAL frogmen appeared in the levels "The Only Easy Day...Was Yesterday" (the SEALs' motto) and "The Gulag" where they provide Task Force 141 with deep-dive suits and the use of the SEAL Delivery Vehicle. The SEALs and TF141 work together to rescue the hostages and free the oil rig from the Russian Ultranationalists.

Multiplayer
In Call of Duty: Modern Warfare 2, the Navy SEALs is also a playable faction in two multiplayer maps. They are the least used faction in Call of Duty: Modern Warfare 2's multiplayer. The only time the player hears a SEAL yell is when a grenade is nearby. Their character models wear both British and American flags, most likely because some of the SEAL models borrow from Task Force 141 deep-dive uniforms from the single-player campaign.They wear distinctive black scuba drysuits and are easy to spot on both maps. Because of their tactical black gear, single player missions involving in being behind enemy lines, and silent voices, they seem to have a black operations style in Call of Duty: Modern Warfare 2. The announcer for the SEALs is Curtis Jackson, better known as "50 Cent", a popular American rapper/actor who did both multiplayer and singleplayer voice-overs for the game.

Special Ops
The player also plays as a Navy SEAL in three Special Ops missions: Breach & Clear, Wetwork, and Armor Piercing.

Call of Duty: Modern Warfare 3
A US Navy SEAL team assists Derek "Frost" Westbrook and Sandman in taking down a Russian attack submarine in New York Harbor during "Hunter Killer".

Two unused emblems can be found in game files.

Call of Duty: Modern Warfare 2

 * Robot
 * Zach
 * Worm
 * Peasant

Call of Duty: Modern Warfare 3

 * SEAL Leader

Assault Rifles

 * M4A1
 * ACR
 * SCAR-H
 * M16A4

Submachine Guns

 * MP5K
 * MP5

Light Machine Guns

 * M240
 * LSAT

Shotguns

 * M1014

Sniper Rifles

 * M14 EBR
 * Barrett .50cal

Handguns

 * M9
 * USP .45

Launchers

 * M203
 * AT4

Modern Warfare 2

 * "Take 'em down!" -Once a Multiplayer Match begins.
 * "UAV online." -When a UAV Recon is called in.
 * "Heads up, enemy UAV spotted!" -When an enemy UAV is in the air.
 * “Counter-UAV up, they're blind!" -When friendly Counter UAV is up.
 * “Enemy AC-130 above!" -When an enemy AC-130 is in the air.
 * “Tango down." -Killed an enemy.
 * “Target Neutralized." - Killed an enemy with an explosive.
 * “Popping Smoke." - When throwing smoke.
 * “Frag out!" -When throwing a fragmentation grenade.
 * “Grenade!" - When an enemy grenade lands near by.
 * “Throwing a flashbang!" - After throwing a flashbang.
 * “Flash out." - After throwing a flashbang.
 * “Tossin' stun grenade." - After throwing a stun.
 * “Planting Claymore." - After planting a Claymore.
 * “Throwing C4." - After throwing/planting C4
 * “Changing mag." - Reloading.
 * "Cover me, Im reloading." - Reloading.
 * “Reloading." - Reloading.
 * “Mission failed, we'll get 'em next time SEALs." - When SEALs lose a match.
 * “Suck it up, the war's not over. - When SEALs lose a match.
 * “Mission failed, hit them harder next time." - When SEALs lose a match.
 * “Your work is appreciated, well done." - When SEALs win a match.
 * “Good job SEALs, mission accomplished." - When SEALs win a match.
 * “We've been EMP'd, electronics are down!" - SEALs enemy EMP announcement.
 * “EMP up! Their electronics are offline!" - SEALs friendly EMP announcement.
 * “It's a draw. Stand down." - SEALs match draw announcement.
 * “Tactical Nuke ready for launch." - When the player has obtained a nuke.
 * “Tactical Nuke incoming, we're done!" - When the enemy has launched a nuke.
 * “Tactical Nuke incoming!" - When a friendly nuke is inbound.

Trivia

 * Rapper/Actor Curtis "50 Cent" Jackson provides the voice acting for the Navy SEALs' multiplayer announcer.
 * Despite being an American special operations unit, in multiplayer some of the Navy SEALs wear British flag patches. This is due to the Navy SEALs character models being borrowed from Task Force 141 scuba divers in the missions "The Only Easy Day...Was Yesterday" & "The Gulag", who are of both American and British nationality. There is also a small chance that the character model for John "Soap" MacTavish can be used in multiplayer.
 * The SEALs in multiplayer mode are relatively quiet, whispering lines in a southern accent, never shouting at all, unless they or any enemy players throw a grenade.
 * Though the Navy SEALs are playable in multiplayer, they are not controllable in the singleplayer campaign. They were originally going to be playable in the campaign, which inspired the mission The Only Easy Day... Was Yesterday.
 * The Navy SEALs multiplayer faction only appears in 2 maps, making it the least used faction in-game. There have been questions about why they are a faction in the multiplayer map, Karachi, and the reason being is because Karachi is a map based on Call of Duty 4: Modern Warfare's single player mission, Shock and Awe, where SEAL Team Six is mentioned trying to disarm the nuclear bomb. It can be seen next to the SEALs spawn that they came to Karachi on zodiacs and a submarine and ported on the edge of the city. Evidence of Karachi being nuked can be seen around the map, as the map is very dilapidated, run-down, and dirty looking.
 * The full Navy SEALs victory music is also heard during the boat chase in "Endgame".
 * When the Rangers meet the SEALs on top of the roof in "Of Their Own Accord", the SEALs are wearing the same type of uniform as the Rangers, as opposed to their wetsuits.This is one of the only times they are depicted like that.
 * The SEALs riot shield character model is the same as that of the Shadow Company's.
 * The SEALs seem to be the only faction to say, "We're done!" when an enemy nuke is activated.
 * The Navy SEALs multiplayer announcer appears to be the calmest from all factions.
 * When playing the German and Spanish versions of Call of Duty: Modern Warfare 2, if the player picks up the bomb in any bomb-objective mode, the announcer will say it in English. This is possibly just a file mistake.
 * In the intro of the Modern Warfare 3 mission "Return To Sender", when the SAS list of their KIA soldiers is shown, most of the faces are the character models of the Navy SEALs.
 * Navy SEALS are the first navy faction that is playable on Multiplayer.
 * In the Modern Warfare 3 multiplayer trailer, there is a care package and shows Navy SEALS on it, but did not appear on the game.

Videos
Navy SEALs' spawn theme. Navy SEALs' victory theme. Navy SEALs' defeat theme.