KCTS-TV (channel 9), branded Cascade PBS, is a PBS member television station in Seattle, Washington, United States, owned by Cascade Public Media. The station's studios are located at Broadway and Boren Avenue in Seattle's First Hill neighborhood, and its transmitter is located at 18th Avenue and East Madison Street on the city's Capitol Hill.

KCTS-TV is the primary PBS member station for the Seattle–Tacoma market, serving alongside Tacoma-licensed KBTC-TV (channel 28), which is owned by Bates Technical College. KCTS-TV also services parts of British Columbia, Canada.

Originally owned and operated by the University of Washington, KCTS-TV became a community licensee in 1987. In 2015, it was announced that the station would merge with Crosscut.com to form Cascade Public Media.

KYVE (channel 47) in Yakima operates as a semi-satellite of KCTS-TV, serving as the PBS member station for the western portion of the Yakima–Tri-Cities market. KYVE's transmitter is located on Ahtanum Ridge.

KCTS was founded by the University of Washington (UW), the station's original licensee. It was a sister station to KUOW-FM, which UW put on the air in 1951. It was originally to have gone on the air under the callsign KUOW-TV, but it instead assumed the callsign KCTS, meaning Community Television Service, to avoid singling out a member of its initial sponsoring group. Sponsors at the time included UW, Seattle Public Schools, King County Public Schools, Seattle University, Seattle Pacific College, and the Seattle Public Library. A studio for KCTS was set up on the UW campus at 15th Avenue NE and NE Campus Parkway, with equipment donated by KING-TV owner Dorothy Bullitt.

The station aired its first test pattern on November 18, 1954; a fire at its studio the following day caused extensive damage to its equipment, but suppliers expedited shipments of replacement equipment such that they all arrived within a week after the fire, avoiding a potential delay to its planned regular programming. KCTS began broadcasting at 7 p.m. on December 7, first airing a five-minute program preview hosted by UW professor and program director Milo Ryan before switching to an abridged performance of Felix Mendelssohn's Elijah by the Seattle Pacific College Choir. Initially, it aired only two preview programs weekly; however, regular programming did not commence until nearly a month later on January 5, 1955, with the inaugural program featuring Governor Arthur B. Langlie as principal speaker. It had three telecast periods throughout the afternoon and evening during weekdays.

During the 1950s and 1960s, KCTS primarily supplied classroom instructional programs used in Washington State's K–12 schools, plus National Educational Television (NET) programs. Outside of schoolrooms, KCTS's audience among the general public was somewhat limited, and most programming was in black-and-white until the mid-1970s (although the station did install color capability in 1967). In 1970, NET was absorbed into the newly created Public Broadcasting Service (PBS), which commenced broadcasting on October 5. As a PBS member station, KCTS began offering a vastly enhanced scope of programming for the general public, including British programming.

Thanks to a major fundraising drive during the mid-1980s, KCTS moved to new studio space on the Seattle Center campus in October 1986 and would remain there until 2024. In 1987, UW spun off KCTS, and the station became a community licensee, thus separating it from KUOW-FM.