Shasta County is a county located in the northern portion of the U.S. state of California. The county occupies the northern reaches of the Sacramento Valley, with portions extending into the southern reaches of the Cascade Range.

As of 2000 the population was 163,256. The county seat and by far the largest city is Redding. Among the tourist attractions in Shasta County are Shasta Lake, Lassen Peak, and the Sundial Bridge. Shasta County was one of the original counties of California, created in 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.