The Yuba County Five were a group of young men from Yuba County, California, United States, each with mild intellectual disabilities or psychiatric conditions, who were reported missing after attending a college basketball game at California State University, Chico (also known as Chico State), on the night of February 24, 1978. Four of them—Bill Sterling, 29; Jack Huett, 24; Ted Weiher, 32; and Jack Madruga, 30—were later found dead; the fifth, Gary Mathias, 25, has never been found.

Several days after their disappearance, Madruga's car, a 1969 Mercury Montego in which the group had driven to Chico, was found abandoned in a remote area of Plumas National Forest, on a high mountain dirt road that was far out of their way back to Yuba County. Investigators could not determine why the car was abandoned, as it was in good working order and could easily have been pushed out of the snowpack it was in. At that time, no trace of the men was found.

In June, 1978, four of the men's bodies were discovered after the snow had melted. Ted Weiher was found inside a United States Forest Service (USFS) trailer some 20 miles north of the abandoned car. Only bones were left of Jack Madruga, Bill Sterling, and Jackie Huett as a result of scavenging animals; Weiher had apparently lived for as long as three months after the men were last seen, starving to death despite an ample supply of food and heating materials in and near the trailer. Weiher was missing his shoes; investigators found Mathias' own shoes in the USFS trailer, suggesting Mathias also survived for some time beyond the group's last sighting.

A local man later came forward, claiming that he had spent the same night in his own car a short distance away from where the Mercury was found. The witness told police that he had seen and heard people around his car that night, and twice called for help, only for them to grow silent and turn off their flashlights. This, and the considerable distance from the car to where the bodies were found, has led to suspicions of foul play.