For years, Donald Trump publicly insisted that he paid no attention to late-night television. He dismissed it as trivial, irrelevant, and beneath the dignity of the presidency. One host in particular, he said repeatedly, was “boring,” “failing,” and “unwatchable.” “Nobody watches him,” Mr. Trump declared.

Behind closed doors, however, the story told by his own staff was strikingly different.

According to multiple former aides, described in books, interviews, and post-administration accounts, Mr. Trump was not merely aware of late-night comedy. He was deeply engaged with it—especially Stephen Colbert, whose satirical monologues on The Late Show with Stephen Colbert frequently targeted the president during his time in office.

Former advisers say Mr. Trump watched television obsessively, often for hours a day, with a particular focus on cable news and programs that mentioned him by name. Late-night comedy, far from being ignored, became a recurring source of irritation. Staff members described a predictable routine: The Late Show aired at 11:35 p.m. Eastern time. By midnight or shortly thereafter, presidential tweets would often follow—angry, personal, and unmistakably responsive to jokes that had just aired.

“He claimed he never watched,” one former official said in an interview cited in multiple accounts, “but he knew every joke.”

Perhaps the clearest confirmation came from Stephanie Grisham, who described Mr. Trump’s television habits in her memoir. She recalled that he was acutely aware of how he was portrayed and took mockery personally, especially when it came from entertainers rather than political opponents. In her account, Mr. Trump could recount specific punchlines, insults, and even audience reactions—details difficult to reconcile with his public insistence that he did not watch.

To aides, the contradiction became familiar and exhausting. Publicly, the president portrayed himself as indifferent to comedians. Privately, he fumed over them. He demanded to know why audiences laughed. He questioned the legitimacy of the humor. He suggested shows should be canceled. And despite repeated advice from advisers to ignore the mockery, he rarely did.

The attacks, former staff members said, were rarely strategic. They were emotional and immediate. Tweets labeling Mr. Colbert “no talent” or “a low life” appeared to respond directly to the previous night’s monologue. Aides learned to brace themselves after each broadcast, anticipating that another round of late-night grievances would spill into the early morning news cycle.

The fixation revealed something deeper than a president with an unusually heavy television habit. Former officials say it underscored Mr. Trump’s intense sensitivity to ridicule. While criticism from political rivals could be dismissed as partisan, mockery—especially when delivered with laughter—cut more deeply. Comedy challenged not just his policies but his image, and image, aides say, mattered above all else.

This gap between public posture and private behavior also complicated the daily work of the White House. Managing the president’s reactions to comedians became, in effect, part of the job. Advisers attempted damage control, urging restraint and focus. They warned that responding only amplified the jokes. The advice seldom prevailed.

In public, Mr. Trump insisted that Mr. Colbert was irrelevant. In private, he proved to be the show’s most attentive viewer.

Only after Mr. Trump left office did these accounts begin to coalesce into a fuller picture, as former staff members spoke more freely about what they had witnessed. Together, they suggest a presidency shaped not only by policy battles and partisan conflict, but also by a nightly ritual of watching, reacting, and responding to satire.

The irony, former aides observed, was hard to miss: a president who claimed he did not care, yet could not look away.