If any one show has represented the post-9/11 era on television, it is “24,” the Fox drama that has offered counterterrorism as entertainment for nine years.

On “24,” torture saves lives. On “24,” phones are tapped, plots are disrupted, terrorists are killed, and one man, Jack Bauer, will stop at nothing to protect the American people. For viewers, “24” is part sum of all fears, part wish fulfillment in an age of shadowy enemies.

For Fox, the show’s trademark clock is about to stop ticking. Nearly a decade after the Sept. 11, 2001, attacks that so heavily influenced people’s perceptions of the series, cast and crew members said they were told on Friday that it had been canceled.

In an interview early this month, as the network was weighing its options, its entertainment president, Kevin Reilly, said, “It’s a hard decision for all involved.”