Shasta County is a county located in the northern portion of the U.S. state of California, in the Cascade Mountains. As of 2000 the population was 163,256. The county seat is Redding.

Shasta County was one of the original counties of California, created on 18 February 1850 at the time of statehood. Parts of the county's territory were given to Siskiyou County in 1852, and to Tehama County in 1856.

The county was named after Mount Shasta; the name "Shasta" is derived from the English equivalent for the name of an Indian tribe that once lived in the area. The name of the tribe was spelled in various ways until the present version was used when the county was established. Originally Mount Shasta was within the county, but it is now part of Siskiyou County, to the north. Its 14,179-foot peak is visible throughout most of Shasta County.