He is the estranged father of the show's main character Jack Bauer and Jack's brother Graem. Phillip is a recurring character, and not part of the main cast. He and his son Graem are involved in a company/organization known as BXJ Technologies, which was contracted by Russian government officials to dismantle several high-yield nuclear devices. However, BXJ secretly arranged for Dmitri Gredenko to obtain the nukes. He is shown to do what is best for himself, as shown when he kills his own son Graem to prevent him from talking about Phillip's involvement with Day 6.
According to a conversation between Jack and Marilyn, Phillip and Jack were on rough terms for more than 20 years, well before Day 1 (though Jack officially left the family shortly after Teri's funeral about nine years before Day 6).
Marilyn even suggested at one point that Jack may have joined the military in defiance of Phillip's offering Jack a job at BXJ Technologies, Phillip's company.
He is a suspect in the terrorist attacks of the day early on. In the 6th episode of the season ("11:00 AM - 12:00 PM"), Jack is attacked and about to be killed by some men, when Phillip Bauer intervenes and says, "He's my son." While the two men keep Jack in custody, Jack explains some of what he knows. When Jack pushes his father, Phillip relents and allows Jack to call CTU. Before he can, though, Graem orders the men not to let Jack go. When Phillip says that Graem cannot do that, that the men are Phillip's employees, Graem interjects and tells his father that the men are, in fact, working for Graem. The episode ends with both Phillip and Jack in the custody of the two men in the back of a van.
In the seventh episode, Phillip speaks with Graem and it is revealed that Phillip Bauer is the real mastermind. Phillip is disappointed Graem told Jack the truth about Day 5, and says that he may have told Jack too much. He injects Graem with a syringe, causing him to go into cardiac arrest and die. Phillip claims that his son has just had a seizure and yells for help to divert suspicion away from him and his involvement in the day's plot. Because Jack had been torturing Graem earlier that hour with Hyoscine-pentothal, blame is deflected to him.
After Graem is brought to the CTU morgue, Phillip rifles through his belongings, erasing all the contacts from Graem's cell phone. Once safely away from listening ears, he phones a subordinate and tells them they must kill Dmitri Gredenko (a key figure in the day's attacks) before CTU can apprehend him, realizing Gredenko knows too much about Phillip's involvement in the day's events and thus could implicate him if interrogated. Gredenko is not eliminated from Phillip's men, having eluded them, though he dies later on from the blood loss suffered after his arm got cut off by Abu Fayed.
He then notices a private conversation between Jack and Graem's widow, Marilyn Bauer, where Marilyn recalls Graem going to a house for a clandestine meeting with men who spoke Russian. When Marilyn is convinced to help Jack find this house, Phillip innocently offers to take Marilyn's son, Josh Bauer, back to their home. After leaving CTU, however, Phillip uses Josh to blackmail Marilyn into setting a trap for Jack. After Jack rescues Marilyn and Milo Pressman, he learns of his father's involvement. In an attempt to retrieve Joshua, Phillip tells Jack that Gredenko blackmailed him about his involvement in David Palmer's death and that he did not know that the nuclear bombs were targeted for America. Right as it appears he is going to kill Jack, he vanishes, leaving behind a phone number. When Jack calls the number, he reaches former President Charles Logan, whom Phillip and Graem directed to act out the conspiracy in Day 5.
He is seen later in the day repairing the sub-circuit board from one of the Russian suitcase nukes for Cheng Zhi, in exchange for custody of his grandson. He was the one who provided the codes necessary for Cheng Zhi's men to infiltrate CTU.
Phillip plans now to escape to China with Josh in tow, citing he feels America is ungrateful for his and Graem's actions. To this end, Phillip betrays Cheng when he's unsuccessful in retrieving his grandson and then bargains with Acting President Noah Daniels for Josh and safe passage out of the US. However, it is revealed during the 4:00-5:00 am hour, that Phillip is secretly colluding with Cheng and the Chinese again, and that Phillip has no intentions of giving up the Sub-Circuit Board.
When Mike Doyle is about to exchange Josh for the Board, Phillip gives him a decoy board, rigged with explosives, that leaves Doyle seriously wounded and possibly blind in one eye.
In the season finale, Phillip is shot by his grandson Josh Bauer while trying to flee the oil rig on an escape boat tracked by a Chinese submarine. He refuses to follow Jack to the escape helicopter to meet Bill and his grandson Josh and is last seen lying beside his boat just seconds before an air strike completely obliterates the oil rig, most likely killing him.
Kiefer Sutherland's real life father Donald Sutherland was asked to play the role of Philip, but he said he would only take on the role if they would have 'the same sort of relationship Sean Connery had with Harrison Ford (in Indiana Jones and the Last Crusade)'. Upon hearing that Philip Bauer would be a terrorist and one the main antagonists of season 6, he turned the role down.