Before the events of the novel, it is suggested that Barlow's original name or alias was Breichen and that he was an Austrian nobleman. As Breichen, Barlow corresponded for twelve years with Hubert "Hubie" Marsten, a former Depression-era hitman living in Jerusalem's Lot, Maine. Marsten murdered his wife and committed suicide, but not before burning his letters with Barlow. The novel strongly implies that Marsten entered into an agreement with Barlow that allowed him to eventually come to Jerusalem's Lot.
In 1975, Barlow arrives the town of Jerusalem's Lot in a box shipped overseas by his human assistant, Richard Straker. The two take residence in Marsten's abandoned mansion, considered haunted by the townsfolk. Barlow and Straker pose as antiques dealers and open a shop in the town; Straker tends to the shop and handles business arrangements while Barlow is seldom seen in public. Straker kidnaps a local boy, Ralphie Glick, and makes a human sacrifice of the child in an appeasement ritual. Ralphie's brother, Danny, becomes a vampire and begins to infect other locals.
Barlow makes his first appearance in the book when he encounters Dud Rogers, a hunchbacked dump custodian. Barlow also comes upon Corey Bryant, a young telephone worker who has been tortured and ordered to leave town by Reggie Sawyer, the man Bryant was cuckolding. Knowing their desires, Barlow claims Rogers and Bryant as his first victims.
Danny Glick later pays a night-time visit to one of his schoolmates, Mark Petrie. However, Mark, an intelligent and resourceful child, identifies Glick as a vampire and drives him off with a plastic cross. Mark sneaks into the Marsten House the next day with Susan Norton, intending to kill Barlow. However, they are both captured by Straker; Susan is bitten by Barlow and becomes a vampire, but Mark manages to escape, mortally wounding Straker in the process. Straker is later found hanging upside down, having been drained of his blood by Barlow. Petrie informs Susan's boyfriend, writer Ben Mears, of Susan's fate, and becomes part of the effort to kill the town's vampires, together with Ben, the Catholic priest Father Callahan, doctor Jimmy Cody and the Lot's high school English teacher, Matt Burke. Susan visits Mark at night, entreating him to let her in as "there are lots more of us now" and promising to "kiss him all over." Mark drives her away, as he had Danny Glick, using the same plastic cross.
When Father Callahan and Mark head over to Mark's parents to explain the danger the family is in, the power is suddenly cut and Barlow appears. He kills Mark's parents by smashing their heads together, but does not infect them. Barlow then takes Mark hostage briefly. Callahan pulls out his cross in an attempt to drive him off, and for a time it works, until Barlow challenges him to throw away the cross. Callahan, not having faith enough to do so, is soon overwhelmed by Barlow, who takes the now-useless cross and snaps it in two, and Callahan is forced by Barlow to drink the vampire's blood.
By now Mark has escaped, part of Barlow's deal with Callahan, and has fled to warn the others. In the end of the book, Barlow is killed by Ben Mears and Mark Petrie in the basement of Eva Miller's boarding house.
In the Dark Tower series, it is revealed that Barlow is a type one vampire, capable of hibernating for centuries and is highly intelligent and cunning. However, seems to appear more human than the other type one vampires.
In Salem's Lot (1979), Barlow was significantly different from his novel counterpart; while Kurt Barlow in the novel resembles an ordinary human being, in the 1979 mini-series, he is depicted with a monstrous (Nosferatu-like) appearance. Interestingly enough, in The Dark Tower, it is mentioned in the beginning that "Type One" vampires (such as Barlow) are horribly disfigured, mutant-like creatures whose teeth grow out so wildly that they cannot close their mouths.
This version of Barlow has a variety of supernatural powers, such as telekinesis; he opens a locked cell door with a wave of his hand, moves his own coffin along with the crate (which is unnaturally freezing cold to the touch) that it is inside, and causes the Petries' entire house to shake before entering.
1995 radio drama
In the 1995 BBC radio dramatization of 'Salem's Lot, Barlow was voiced by Doug Bradley.
In the 2004 miniseries adapted from the novel, Barlow is portrayed by Rutger Hauer. He is a sophisticated, well-dressed older gentleman and, at first glance, his only difference from the rest of the community is his mildly anachronistic appearance (his dress and behavior seem to come from an earlier time). As opposed to the Nosferatu-type creature that Barlow was portrayed as in the 1979 mini-series, this portrayal is more in keeping with King's original source novel.
Richard Throckett Straker was Barlow's 'familiar' or human thrall. All of Barlow's business concerns are enacted by him. He bought the Marsten house and prepared the way for his master. After Mark Petrie wounded Straker during his escape from the Marsten house, Straker was drained of his blood by Barlow who was unable to resist feeding on his servant's freshly spilled blood. Barlow was furious at this turn of events, as he considered Straker the best servant he had ever possessed.
In Salem's Lot (1979), Straker was the main antagonist and a more prominent villain than Barlow, unlike the novel, and was alive until the climax of the mini-series. Though seemingly human, this version of Straker turns out to be something more with incredible strength, and it is implied he possesses some kind of supernatural power; he manages to summon a fast wind as he abducts Ralphie Glick in the woods and easily manages to lift Dr. Bill Norton off the ground by himself with little effort, as he impales him on a wall filled with animal horns. He was, however, still mortal and was shot and killed by Ben Mears on the stairs of the Marsten house, though he took several bullets to the abdomen and continued to move until finally succumbing to his wounds. Straker was English in this version (as played by James Mason) and came from London. His name, according to Constable Gillespie, was actually Richard K. Straker, though it remains unknown what the middle initial stood for.
In 'Salem's Lot (2004), Straker's name is once again changed, this time into Richard Thomas Straker. He was portrayed by Donald Sutherland. Although he again has more screen time than Barlow in this version, his role is somewhat reduced from that of the original mini-series. He is also never actually seen in any of the same scenes with Barlow. In this version, he is killed as in the novel and left hanging upside down from the rafters of the Marsten house, drained of his blood. However, it is unclear if he was killed by Barlow, since it is established in the 2004 mini-series that the house itself has some kind of evil entity dwelling inside it that had previously killed Hubie Marsten in a similar way.