The original The Twilight Zone aired on CBS. The network carried Rod Serling's anthology series throughout its original five-season run, from its premiere in 1959 through its final episode in 1964.
CBS scheduled the program as a half-hour anthology for most of its run, although the fourth season experimented with hour-long episodes. Each installment told a self-contained story, allowing the network to present changing casts, settings, and genres under one title. The format helped The Twilight Zone stand apart from conventional continuing dramas and sitcoms of the era.
The show initially faced uncertainty because its early ratings were weaker than CBS hoped, but it survived and developed a devoted audience. Its competition included programs on ABC and NBC, which can cause confusion when people remember the broader television landscape of the period. PBS was founded later, in 1970, so it was not the original broadcaster. The CBS connection also distinguishes the 1959 series from later Twilight Zone revivals, which aired on different networks.