Thomas Creek is a stream, about 35 miles (56 km) long, in Linn County in the U.S. state of Oregon.

Beginning in Willamette National Forest on the western slopes of the Cascade Range, the creek flows generally west through Santiam State Forest and farmland to meet the South Santiam River west of Scio.

[7] Three covered bridges, all listed on the National Register of Historic Places, carry traffic over the creek.

The drop in elevation on its upper reaches, coupled with its flow volume, make it suitable at times for whitewater canoes and kayaks.

It begins on the western slopes of the Cascade Range at an elevation of about 3,700 feet (1,100 m) above sea level southwest of Detroit Lake, which is on the North Santiam River.

[8] Downstream of Jordan, other small tributaries enter before Thomas Creek flows by a stream gauge operated by the United States Geological Survey at RM 14.2.

[8] Based on data collected from 1962 to 1987 and from 2002 to 2013, the average discharge of Thomas Creek at the stream gauge near Scio was 487 cubic feet per second (13.8 m3/s).

[9] All of Scio was flooded in December 1964, when Thomas Creek and Peters Ditch overflowed their banks.

[18] The road bridge, a 120-foot (37 m) structure of the Howe truss type, was built in 1939, damaged and closed in 1997, repaired and re-opened in 1998.

In 1989, a group in Sweet Home raised additional funds to have the bridge moved and installed across Ames Creek in that city's Sankey Park.

[13] The creek supports populations of smallmouth bass and cutthroat trout as well as small runs of Chinook salmon and steelhead.

Hazards include fast water, rocky ledges, submerged or floating logs, a "nasty chute", and a debris dam.