Theo Stoller on Day 5
|Portrayed by||Henry Ian Cusick|
|First appearance||Day 5: 7:00 PM – 8:00 PM|
|Last appearance||Day 5: 8:00 PM – 9:00 PM|
Theo Stoller is a undercover German Federal Intelligence agent who was working with United States government.
 Day 5
During Day 5, Theo Stoller is first seen with Collette Stenger, an information broker, whom he has been engaging in a romantic relationship with in hopes of uncovering the terrorist clients she works with. When Theo attempts to gather some information in an attempt to "help her", Collette storms off and says she will meet Theo later at the airport. Soon afterward, Theo discovers armed men raiding the building, and in an attempt to protect himself, he captures Curtis Manning and threatens to kill him.
The men make Theo aware that they are from CTU Los Angeles. Jack Bauer tells Theo that they are needing to capture Collette and interrogate her for her alliance with a known terrorist that is threatening the city. Theo agrees to help after Jack agrees to give him the WET List, which offers the names of known terrorists around the world that have been gathered by federal agencies.
Back at CTU, Karen Hayes and Bill Buchanan order Jack to get the list back from Stoller, but he refuses. Soon, Collette arrives, and Theo stalls her as Jack identifies her as the suspect and takes her into custody. During this time, Stoller is seen driving away in a car, and as he leaves, the memory card attached to the WET List catches fire. Jack is seen calling Theo and apologizing for their actions, and promises to help build his case in the future.