Criminal Minds' "Blood Relations" unnamed serial killer is one of the few to completely evade the BAU. Criminal Minds debuted in 2005 and quickly became one of the biggest procedurals on television. The series revolves around an elite team of FBI profilers who are tasked with hunting down killers who often employ unique methods. Criminal Minds received two spin-offs with Suspect Behavior and Beyond Borders, though neither lasted long. The main series itself, however, ran until 2020 and ended after 15 seasons.
While not quite a horror show, Criminal Minds often featured killers with particularly disturbing or gory techniques. Some of the most memorable include C. Thomas Howell's George Foyet - AKA The Reaper - or Brad Dourif (Child's Play's Chucky) as Adam Rain, who turned victims into living dolls. Despite the number of killers the BAU faced throughout the show's long run, very few managed to completely evade the team. One such instance occurred with season 9's "Blood Relations," where the episode's "unsub" killer made a getaway.
Criminal Minds' "Blood Relations" was helmed by series star - and horror fan - Matthew Gray Gubler, and involves a feud between two families in West Virginia apparently turning bloody. The episode is also notable for genre icons like Tobin Bell (AKA Jigsaw from the Saw movies) and Adrienne Barbeau, star of John Carpenter's cult classic The Fog (which has a familial connection) appearing in major roles, with the former playing Malachi Lee and the latter playing Cissy Howard. While the Lee and Howard clans are feuding with each other, it's later revealed that Cissy was once Magdalene Lee, Malachi's sister. The pair had an incestuous affair that resulted in the birth of "Blood Relations" killer, who Cissy gave away to a woman living in the woods who raised him. Following her death, the killer - played by Take This Lollipop's Bill Oberst, Jr. - set a plan in place, where he killed Cissy and Malachi's sons and planned to kill her until she convinced him to flee instead.
In Criminal Minds' "Blood Relations" finale, the woodsman killer escapes after setting a Saw-style trap that slays a police officer. He vanishes into some nearby water, where the BAU fire many rounds into the water in hopes of killing him. This Criminal Minds episode ends with a couple coming to an isolated cabin to spend some quality time - only for the man to get snagged around the neck by the unsub's signature barbed wire. The killer orders him to turn over his keys, and "Blood Relations" ends as he completes a three-second countdown.
It's an unusual ending for a Criminal Minds episode, and while the couple was later confirmed to have survived this encounter, "Blood Relations" killer was never caught. That puts him in company like season 8's Darlene Beckett or Shane Wyland as killers that evaded the BAU. Given that Gubler is such a big horror fan, he likely wanted to give viewers a little chill with the thought the killer is still haunting the woods.