Tony Almeida is an agent at the Los Angeles Counter-Terrorist Unit, frequently working in a support role for Jack Bauer.
Tony Almeida served as an agent at Los Angeles CTU, and was in the CTU chain of command behind Jack Bauer and Nina Myers. When Nina was revealed as a traitor at the end of Day One and Jack left CTU, Tony became the second in command of CTU under George Mason.
When Mason died during the events of Day Two, Tony took over as head of CTU.
During the events of Day Three, Tony's wife and fellow CTU agent Michelle Dessler was taken hostage by terrorist Stephen Saunders. Saunders demanded that Tony shift agents away from a corner of the perimeter so that he could escape, otherwise he would kill her. Almeida did what Saunders wanted in order to save Michelle, and was relieved of his command and sent to prison, although he received a reduced sentence.
Upon his release from prison, Michelle left Tony because he was becoming a drunk. He shacked up with another woman until Jack needed his help on Day Four. Tony helped Jack and saved his life and that of Audrey Raines, and continued working with Bauer throughout the rest of the day. Tony returned to CTU on a provisional basis, working for Jack. He reconnected with his former wife there, and the two eventually decided to leave CTU when everything was over with and start a new life together.
In a twist on the events of Day Three, Tony was captured by assassin Mandy, who demanded that Michelle, who was serving as head of CTU after the departure of former CTU head Erin Driscoll, move the LAPD out of the area so that she could escape, or else she would kill Tony. Michelle refused Mandy's demands, but Jack was able to save Tony anyway. Tony went on to play an integral part in faking Jack's death.