This is a list of characters who were antagonists during Day 3.
Salazar drug ring
- Ramon Salazar: Mexican drug Lord, thought to have threatened L.A. with the Cordilla virus, broken out of jail by Jack. Killed when virus capsule set by Amador exploded.
- Hector Salazar: Younger brother of Ramon. Handled the drug "empire" after Ramon's incarceration and helped from Mexico. Killed by Ramon.
- David Gomez: Shot Tony Almeida at the mall so Kyle Singer could escape. Later he was killed in a CTU raid.
- Tomas: Lieutenant of the Salazars who convinced Ramon not to kill Jack.
- Pedro: Henchman of the Salazars, killed by Jack on the plane during the flight.
- Sandra: Dancer or escort who worked as an attendant for the Salazars.
- Eduardo: Henchman of the Salazars, tortured Chase Edmunds. Died when Claudia and Chase overpowered him.
- Emilio: Henchman working for the Salazars. Shot Claudia then shot by Chase.
- Pablo: A henchman working for Hector, then for Ramon. Knocked out by Chase before the Delta Force attacked the Salazar camp.
- Felipe: A henchman working for Hector, along with Pablo.
- Luis: A henchman working for Ramon who kept watch over Nina Myers
- Zach Parker: Drug addict and small time dealer who hired Kyle Singer to be a cocaine mule for Carlos Corretja.
- Ed: An accomplice of Parker.
- Carlos Corretja: Mid-level narcotics distributor for Hector in Tijuana who hired Zach Parker to move a single bag of "cocaine" across the border.
Stephen Saunders bioterrorism group
- Stephen Saunders: Member of Jack's Nightfall team in Kosovo. Became a bio-terrorist mastermind obsessed with dismantling the foreign empire of the United States, and used the Cordilla virus to coerce President David Palmer.
- Diana White: Former lover of Stephen Saunders. Saunders blackmailed her rich brothel clients to finance his terrorist operations, and later had her killed by attacking the MI6 HQ in Los Angeles in order to impede CTU and MI6's investigations.
- Marcus Alvers: Close associate of Michael Amador. He was the connection between Amador and Saunders, and was also one of Saunders' virus couriers; planted a vial in the Chandler Plaza Hotel. Killed either by the virus or shot by Michelle Dessler as part of their deal.
- Michael Amador: Auctioneer of the virus in Mexico. Saunders' associate. Saunders' men planted a bomb in his escape car because he was being followed.
- Osterlind: Right-hand man for Saunders, and coordinated most of the couriers' movements. Killed by Saunders when he decided to flee from the authorities.
- Arthur Rabens: The Los Angeles virus courier for Saunders, last one to release the virus. Killed by Jack Bauer in the school.
- Ian: The San Francisco virus courier for Saunders.
- (Virus courier): An unnamed virus courier for Saunders, sent to an unspecified city.
- Kevin: Henchman who kidnapped and guarded Michelle; she tricked him and escaped after knocking him out.
- Frederick: Henchman, captor of Michelle Dessler. Shot by Tony Almeida in a shootout.
- Pach: Henchman sent to destroy the MI6 database; was foiled by Jack and Chase.
- Young: Henchman sent to destroy the MI6 database; was foiled by Jack and Chase.
- Dorman: Expendable operative of Saunders who unwittingly went on a suicide mission to pick up Amador.
- Lennox: Young man hired by Saunders to keep tabs on his daughter Jane while at college.
Others
- Nina Myers: Hired by an unknown client to purchase the virus for $240 million from Michael Amador. She was eventually captured by CTU, tricked Jack to release a computer virus in the CTU system, tortured, escaped, killed several people in CTU, and finally, after 4 years, she was slain by Jack to fulfill his revenge for killing his wife, Teri.
- Cale: Nina's partner, working for the same client.
- Peel: a prisoner that forced Jack and Ramon to play Russian roulette during the riot
- Prison riot inmate: another inmate during the prison riot
- Sherry Palmer: responsible for the death of Alan Milliken
- Alan Milliken: tried to blackmail President David Palmer, in order to fire his brother, Wayne Palmer
Miscellaneous
- Gael Ortega: Agent at CTU Los Angeles, Gael Ortega provided information to the Salazars acting as their mole, but was later revealed to be, in fact, working for CTU.
- Kyle Singer: Though he had no knowledge of the plot, Kyle Singer was involved, as he ferried the Salazar's drugs across the Mexican border, and was later suspected of carrying the virus himself.
- Douglas Shaye: Ramon Salazar's lawyer. Murdered by Salazar with a pen becase he knew too much.
- Jeff Benson: Prison guard who murdered Luis Annicon because Salazar had his son hostage. After Annicon was killed, Ramon said that his son would be released. Benson was placed in jail afterwards.
- Yuri: Ukrainian contact of Amador and connection to the original creators of the virus.
- Julia Milliken: could have prevented her husband's death but chose to listen to Sherry
Note
- There were a number of unnamed terrorists and henchmen working for Stephen Saunders, Michael Amador.
- Prior to Day 3, Ari Consul and Sayid Kolobe were two of Stephen's co-conspirators.