Agent Lee Castle

Lee Castle was a CTU field agent during Day 4. He was originally portrayed as a brutal, out-of-line soldier (during his interrogation of Dina Araz, he physically assaulted her, almost putting her into shock), but for the rest of the season he appeared to be a competent field agent. Castle survived until minutes before 5:00 AM, when he is shot to death by Mandy after her capture of Tony Almedia.