Jack Bauer 
Jack Bauer was formerly an agent for the Los Angeles
Counter Terrorist Unit, better known by its acronym, CTU. In the first
season, Serbian terrorists sought revenge for a mission Bauer participated
in in Serbia several years prior. Jack’s wife, Teri, and daughter,
Kim, were taken hostage by the terrorists, and an attempt was made
on the life of then-Senator David Palmer, who authorized the aforementioned
mission. Ultimately, Jack managed to save Palmer and Kim, only to
find that Nina Myers, his ex-lover was a double agent, and had killed
his wife within the very walls of CTU. In the months after, he and
Kim grew further apart, as she blamed him to an extent for the death
of her mother.
Following the incident with his wife, he quit CTU, but
was soon called back for his experience. A suspect Jack had been formerly
undercover with was thought to be involved in a threat to detonate
a nuclear bomb on American soil, and Jack was called back in to help
stop it. Little did Jack know that Nina would be called back in on
the case, and he’d find himself eventually teaming up with her
to stop the bomb. Jack found the bomb, and almost had to give his
life to detonate it on safe soil, since it was impossible to disarm,
but fortunately a colleague, George Mason, already dying of plutonium
poisoning was able to save Jack’s life by sacrificing himself.
Realizing perhaps that his calling in life was at CTU,
Jack rejoined the unit after the nuclear bomb incident. In an undercover
job in Mexico in which he apprehended terrorist Ramon Salazar, Bauer
acquired an addiction to heroin, a substance he claims he was required
to take to maintain his cover. In an elaborate sting operation, Bauer
later broke Salazar out of prison and flew him back to Mexico so that
he could again go undercover and assist the Salazar’s in the
purchase of a deadly virus, which he would then take out of play and
hand over to the United States government. He eventually did stop
the virus attack, although, in the process, he had to capitulate to
terrorist demands by executing Ryan Chappelle, a fellow CTU officer.
Erin Driscoll later fired Bauer for his prior heroin
addiction, although he had come clean at the time, and Bauer is now
employed at the Department of Defense. He is also involved with Audrey
Heller.