The New Children of the Old God are a criminal group in the television series Dirk Gently's Holistic Detective Agency.
In a remote area in the northwestern U.S., they preyed on people, killed them and sold their vehicles; they murdered at least about twenty people that way.
One day one of their members, Jake, happened upon Bart Curlish and Ken where their car had broken down on a forest road. He offered to help them fix it, and proceeded to do that. At night when he was done, he revealed the gang's criminal scheme. Jake then tried to shoot Bart as she came at him, but was unable to hurt her, his gun either missing or misfiring. Bart then took the gun out of his hand and used it to bludgeon him to death.
The biker gang found out about Jake's death and pursued his killers, finding them the next day and crashing Bart's car by shooting the tires. They tied Bart and Ken onto a post in a field, and left them there for a few hours. Then eight bikers (including the Biker Leader) arrived to interrogate and afterwards murder them, asking whether they had been sent by the Cavatos or anyone else, which they denied. Through a string of happenstances, Bart got loose and killed all of them. She and Ken then plundered the bikers' possessions for clothes and equipment, and left on a bike and sidecar at dusk.
- Bart's car crashes into a road sign (Rogue Wall Enthusiasts, 12min mark) which, if taken as canon, places the New Children of the Old God biker story episode in eastern Montana.
It is unknown how large the biker gang was outside of the bikers killed during this incident, and whether the gang was eradicated, became defunct, or continued to exist after this.