Under President Trump, the White House news briefing — once a Sisyphean burden for rumpled reporters — became the hottest reality show in town, a star-making showcase for journalists where heated exchanges went viral and drove big ratings.

So what happens when the protagonist gets written off?

Like a popular actor leaving a sitcom, Sean Spicer resigned on Friday as White House press secretary, a move that deprives the daily briefing of its central character (its hero or its villain, depending on the viewer) and spells the end of an unlikely cottage industry that has sprung up around the man who might already be the most famous press secretary of modern times.

Mr. Spicer’s six-month tenure was a life-changing experience for the figures in his orbit, enhancing careers and fueling national exposure. The actress Melissa McCarthy earned an Emmy nomination for an instantly famous Spicer impression on “Saturday Night Live.” April D. Ryan, a correspondent for the American Urban Radio Networks, leapt to cable news stardom after clashing with Mr. Spicer in the briefing room.

On some days, television news broke into popular soap operas and talk shows to carry Mr. Spicer’s briefings live. Whether a briefing was on- or off-camera — once the idiosyncratic concern of Washington insiders — turned into dinner table conversation around the country. Even the tabloid outlet TMZ got into the act, posting a grainy video of Mr. Spicer being ambushed by a critic at an Apple store in Virginia.

“There’s a fount of material; it’s insatiable,” said Matt Negrin, whose obsessive Twitter chronicling of Mr. Spicer’s daily appearances helped him land a job at “The Daily Show,” where he now produces videos that capture Mr. Spicer’s most memorable malapropisms and gaffes.

Mr. Negrin, who has a six-foot-long canvas poster of Mr. Spicer hanging in his New York apartment (“it looks like he’s looking right into my eyes”), heard of Mr. Spicer’s exit on Friday morning and tweeted, simply, “omg.”

Then he posted a video obituary for Mr. Spicer’s tenure titled, “Sean Spicer’s Daily On-Camera Press Briefings, 2017-2017.” It had been prepared ahead of time.

Other longtime journalists found their lives and careers enhanced during Mr. Spicer’s brief time behind the lectern.

Graphic | All Joking Aside, Here’s How Sean Spicer Shook Up the White House Press Briefing Mr. Spicer typically calls on media organizations outside the mainstream before getting to more traditional news outlets.

Glenn Thrush, the New York Times reporter who broke news of Mr. Spicer’s resignation on Friday, was the subject of a memorable impression from Bobby Moynihan on “Saturday Night Live.” Ms. Ryan, a 20-year veteran of White House coverage, became an in-demand commentator soon after Mr. Spicer chastised her in a televised briefing. On top of a new CNN contract, Ms. Ryan recently appeared as a guest on the CBS program “The Late Show with Stephen Colbert.”

In recent weeks, Mr. Spicer was spending less and less time at the lectern, often replaced by his top deputy, Sarah Huckabee Sanders. The White House has also been insisting that briefings, once big ratings drivers on afternoon cable news, would be audio-only, depriving television audiences of a glimpse of Mr. Spicer’s performance.

Tammy Haddad, a Washington media consultant, echoed others in politics when she said her firm deliberately skipped conference calls during briefing time to keep up on developments.

“It’s a scramble if there is a delay,” Ms. Haddad wrote in an email, “and we have to keep track through Twitter.”

News of Mr. Spicer’s exit prompted speculation that the press secretary would quickly find a new home on television, following in the tradition of former White House aides who land lucrative contracts on cable news.

There is one network, however, where he will not find employment: CNN, which has clashed repeatedly with Mr. Spicer and the Trump administration, said on Friday that it would not hire Mr. Spicer.

Mr. Spicer’s grimaces and often-frowning appearance led some to wonder if the stresses of his job had been eroding his quality of life. But some of his friends in the political world on Friday said that they believed Mr. Spicer would land on his feet.

“Sean will be fine,” said Alex Conant, who led communications for Senator Marco Rubio’s presidential bid.

Mr. Conant added: “Will the White House?”