|Affiliation:||United States government|
|Profession:||United States Senator|
|Played by:||(unknown actor)|
|Episode:||"Day 7: 8:00am-9:00am"|
Marcus Alderbrook was a Senator who, during Day 7, was part of an investigation into human rights violations committed by the disbanded Counter Terrorist Unit in Washington, D.C. The primary investigator was fellow senator Blaine Mayer.
On the third day of the televised senatorial investigation, Senator Alderbrook was present when Senator Mayer called Jack Bauer as a witness to address the issue of torture committed at CTU. Others on the eight-senator panel with Mayer and Alderbrook were Monica Addison, James Gilbert, Richard Horton and Harrison Wakefield. The senators' hearing with Bauer was interrupted by FBI agents Renee Walker and Teller, who had a more pressing need to speak with Bauer: a national security crisis involving Tony Almeida. ("Day 7: 8:00am-9:00am")