Ash Creek is a long second-order tributary to the Niobrara River in Rock County, Nebraska.
Ash Creek rises on the North Fork Elkhorn River divide about southwest of School No. 172 in Holt County and then flows northwest into Rock County to join the Niobrara River about northeast of Mariaville, Nebraska.
Ash Creek drains of area, receives about of precipitation, and is about 2.60% forested.