When Jimmy Kimmel dropped the humor and began a relentless campaign against the latest effort from Senate Republicans to repeal the Affordable Care Act, it was — at the very least — an uncommon moment for him.
While Mr. Kimmel often discusses politics on his show, it is not his main focus and he has rarely — if ever — taken such a serious tone to advocate for or against a single piece of legislation. In the Trump era, late-night hosts speaking out against President Trump are common. Leaving out the jokes, however, is not.
There have been other instances since the advent of late-night television where comedians have substituted political seriousness for punch lines — or combined the two. While these are rare, they can often create powerful moments of television. Or, when comics get involved directly in politics, sometimes it can flop. Just ask Bill Maher.
Here are some examples from over the years.
No late-night host has fought as vigorously or passionately for a piece of legislation as Jon Stewart, the former host of “The Daily Show,” did on behalf of the James Zadroga 9/11 Health and Compensation Act. The bill was to provide health care for emergency medical workers who were sickened in the aftermath of the Sept. 11 terrorist attacks. It was passed in 2011, partially because of Mr. Stewart’s relentless lobbying.
Mr. Stewart dedicated the entire final episode of his show in 2010 to the stalled legislation and even brought on four emergency medical workers for an emotional interview. He did numerous segments attacking Republicans for holding up the bill leading up to that episode. He criticized media outlets for undercovering the story. He badgered Mike Huckabee, the former Arkansas governor and presidential candidate, into supporting the bill.
Even after leaving “The Daily Show,” Mr. Stewart went to Capitol Hill in 2015 to advocate for extending the bill permanently, saying at a rally that he was “embarrassed” that it hadn’t been. He returned to “The Daily Show” for an appearance three months later for another fierce takedown of Congress for holding up the second Zadroga Act.
In September of 2014, Bill Maher, the host of HBO’s “Real Time With Bill Maher,” announced the winner of his “Flip a District” campaign, aiming to unseat a Republican congressman of his viewers’ choosing. They landed on Representative John Kline of Minnesota. Mr. Maher made defeating him a priority, and propped up his Democratic opponent, Mike Obermueller. But less than a week before Election Day, Mr. Maher, in an interview with The New York Times, couldn’t remember his preferred candidate’s name: “It’s not Keith Olbermann, but it’s a name like Keith Olbermann.”
Mr. Maher even traveled to Minnesota to campaign against Mr. Kline. However, “Flip a District” didn’t go well. Mr. Kline won decisively, causing Mr. Maher to post on Twitter, “Well, i guess we picked the wrong week to quit sniffing glue. And flipping Republicans. Enjoy it John Kline, at least people are on to U now.”
As part of his quest to bring attention to the complicated world of campaign finance — and its loopholes — Stephen Colbert, then playing a bloviating conservative on “The Colbert Report,” created a super PAC called “Americans for a Better Tomorrow, Tomorrow” in 2011. It went beyond a running gag on the show. He was approved by the Federal Election Commission in June of that year. Fans donated to the committee en masse: The super PAC raised more than $1 million. It actually paid for advertising criticizing then-Texas Gov. Rick Perry in the run-up to the Ames straw poll in Iowa. The committee encouraged voters to cast their ballot for “Rick Parry.” In early 2012, it ran an attack ad calling the 2012 Republican nominee, Mitt Romney, a serial killer.
Mr. Colbert did an interview — in character — with ABC’s George Stephanopoulos about his exploratory committee:
Mr. Colbert terminated the committee in November of 2012.
John Oliver, the host of HBO’s “Last Week Tonight,” has made net neutrality a pet issue going back to 2014. At the end of one 13-minute segment, Mr. Oliver beseeched his viewers to leave comments on the Federal Communications Commission’s website. It drew hundreds of thousands of comments and emails, causing the F.C.C.’s system to be overrun.
But Mr. Oliver wasn’t done. In another segment this May, Mr. Oliver called on viewers to write to the F.C.C. again to voice displeasure as its chairman, Ajit Pai, was pushing a roll back of the rules overseeing high-speed internet providers established just two years before.
Mr. Oliver’s team created a website to redirect people to the F.C.C.’s comment section: www.gofccyourself.com.
In the heat of the 2008 presidential election between then-Senator Barack H. Obama of Illinois and Senator John McCain of Arizona, Mr. McCain at the last second canceled a scheduled appearance with David Letterman on the “Late Show.”
Mr. McCain announced that he was suspending his campaign and heading to Washington to deal with the financial crisis that had erupted in the waning days of the race. Mr. Letterman assailed Mr. McCain repeatedly for several minutes on his show that night for his decision to cancel his interview while at the same time agreeing to do an interview with Katie Couric on CBS News. Mr. Letterman said, “When you call up at the last minute and cancel, that’s not the John McCain I know.”