Frederick "Warlock" Kaludis is a legendary computer hacker and Matt Farrell's friend. He is slightly overweight and introduces himself by saying that he gained thirty pounds in response to Farrell's comment stating that he lost weight. Warlock is shown not to be fond of police officers, reacting with hostility when he finds out that John McClane is one. He lives with his mother and is a great fan of the Star Wars franchise. He is one of the two terteragonists of the fourth film.
When Farrell and New York cop John McClane arrived in his house, Warlock gets angry when McClane observes that his "command center" is actually a basement. Warlock reluctantly helped McClane and Farrell look for Thomas Gabriel, who he was scared of (and who apparently knew him, given Gabriel calling Warlock a "fat bastard" when contacting him), and is detected by a furious Gabriel who contacts him. While McClane kept Gabriel distracted, Warlock and Farrell tracked him to Woodlawn, where he was hiding. Having learned that Gabriel and his men had McClane's daughter hostage, McClane and Farrell took Warlock's mother's car to go to Woodlawn.
Later, while McClane is driving Gabriel's tractor-trailer, he uses its CB radio to contact Warlock, who refuses to answer to his real name Freddy, only speaking with McClane when he calls him Warlock. McClane asks Warlock to contact Deputy Director Miguel Bowman of the FBI for him and then patch him through, but Warlock refuses as Bowman is the head of the FBI's Cyber Division, and he's a hacker. After McClane informs him that Gabriel has his daughter, Warlock complies and successfully patches McClane through to Bowman, allowing him to lead Bowman and his men to Gabriel's hide-out.