Derek "Frost" Westbrook

Staff Sergeant Derek "Frost" Westbrook is a Delta Force operator assigned to Team Metal, operating under the command of Sandman. Frost is one of the playable characters and one of the main protagonists in Call of Duty: Modern Warfare 3. Frost serves as the tertiary protagonist of Modern Warfare 3.

Operation Kingfish
Frost participated in Operation Kingfish alongside Sandman, John Price, John "Soap" MacTavish, Simon "Ghost" Riley and Gary "Roach" Sanderson. He provided sniper support for Bravo Six before aiding them in trying to find Makarov inside the safehouse. After Makarov was not located, the team was extracted by helicopter, except for Price, who sacrificed his freedom by staying behind, fighting the Russians long enough for the others to escape until he was captured and sent to a gulag.

Delta Force Sergeant
Frost participated in the Battle of New York during the events of "Black Tuesday" and "Hunter Killer". His team, Team Metal, was assigned to destroy a Russian Electronics Jammer on the roof of the Stock Exchange. Facing heavy resistance, Frost and his team manage to disable the Jammer, evacuating aboard a Black Hawk helicopter. They were then pursued by a group of Mi-24 Hind gunships in the skies above New York, which Frost destroyed.

Metal Team is then grouped with a squad of Navy SEALs to take control of a Russian Submarine (acting as a command vessel). Frost and Sandman sneak aboard the sub after an underwater insertion through the Brooklyn Battery Tunnel and re-program the missiles onboard to launch onto the Russian fleet, effectively crippling Russia's seaworthiness and forcing them to retreat as Frost and Sandman make their escape via Zodiac.

Rescuing the Vice President
Their team was later assigned to a hostage situation in Hamburg, Germany involving the Vice President. They get the Vice President and extract him sucessfully. They were sent to Paris, France to capture Makarov's bomb maker Volk under intel by John Price. They also get orders from Overlord to rendezvous with and provide backup to the GIGN forces led by Sabre. After meeting up, they carry out their orders of capturing Volk alive.

Assisting the GIGN
On their way to find Volk, they are met with heavy resistance from Russian soldiers and armored vehicles, but thanks to assistance from an AC-130 gunship, callsign "Warhammer" in the airspace they were able to locate Volk, who was hiding in the catacombs, though Frost got hit by a flashbang. As Volk manages to run away, Frost, his team and the GIGN fight their way to pursue Volk who gets away in a car. Frost's team managed to get in a van and chase Volk throughout the streets of Paris. They later  apprehend Volk and receive orders to take Volk to their extraction point. However, it was compromised and they had to get to the secondary extraction point, which was near the Eiffel Tower. Receiving air support from the AC-130, they managed to get Volk out of the battlefield.

Finding Alena Vorshevsky
Frost's last mission was to rescue the Russian President's daughter Alena Vorshevsky, who was hiding in Berlin, Germany. After fighting through the city to save her, Alena is still captured by Makarov's men and taken to Siberia. There is no clear reason why he was not with his crew to save the Russian president and his daughter.

Trivia

 * If the player looks at his gloves, they will see the logo for Oakley Inc.
 * Frost is the sole survivor of Delta Force's Team Metal.
 * Frost is the only member of Team Metal to have his full name revealed.
 * Frost is one of the two characters in the Modern Warfare Series who is Staff Sgt. (The other character is SSgt. Griggs in Call of Duty 4: Modern Warfare).
 * In multiplayer, there is an emblem of Frost.
 * The Xbox LIVE avatar outfit for the American Special Agent for the FBI class for light machine gun appears very similar to Frost.
 * Crosby from Call of Duty: Black Ops II is dressed very similarly to Frost.
 * Frost is the first playable character in a Modern Warfare campaign to appear in Special Ops missions, specifically "Stay Sharp" and "Charges Set".
 * In Call of Duty: Modern Warfare 3's Spec Ops mission "Toxic Paradise", Overlord calls the player(s) "Metal 0-4" so probably in this mission, one plays as Frost.
 * He is paired up with Sandman the most in the campaign.
 * Along with Roach, Ghost, and Crosby he is the only one to hide his face with balaclava and goggles.
 * Frost's character model is randomly used on Delta Force soldiers in multiplayer, and for randomly generated Delta Force operators including a member of Onyx team.
 * Frost's most used weapon is the M4A1, he uses it in "Black Tuesday", "Iron Lady" and "Goalpost".
 * He is the only character in the game to wield the ACR 6.8 in the campaign.