Television has been a fixture in American life for so long now that on some level almost every show feels like a rerun, a present-day iteration of something we’ve seen before. How often, really, does someone burst through the small screen’s many formulas and deliver something that feels wholly new?

Not often. But that’s exactly what Stephen Colbert did.

It’s true that his comic persona — the blowhard conservative pundit, often in error but never in doubt, with an ego the size of the Grand Canyon — was originally inspired by Fox News host Bill O’Reilly, or “Papa Bear,” as Colbert called him with mock reverence.

But after nine years of Comedy Central’s “The Colbert Report,” which ends Thursday, the pseudo-commentator known as “Stephen Colbert” stands as a groundbreaking creation who could well go down as one of the most unforgettable characters in TV history.

The rise of the real Stephen Colbert — who is retiring his character and heading to CBS to take over David Letterman’s late-night show — dovetailed with the growth and increasing inanity of the cable TV commentariat whose bloviations he so expertly lampooned.

He and the equally quick-witted Jon Stewart emerged as the Ruth and Gehrig of TV satire. (Colbert had been a correspondent on “The Daily Show with Jon Stewart” before going solo in 2005). Their takes were so brilliantly incisive that when actual news unfolded, you would immediately wonder: “What will Stewart and Colbert do with this tonight?”

But Colbert was the bigger innovator. It was he who refined and exemplified the comedy of reductio ad absurdum. Sounding august, even presidential, the hyper-patriot “Stephen Colbert” would intone the word “Nation” as if he were commencing a State of the Union address, then proceed to spew a hilarious geyser of red-white-and-blue nonsense.

The key to the equation was that Colbert seldom broke character onscreen, even when conducting real-time, unscripted interviews with guests. His ersatz pundit manufactured self-aggrandizing feuds with celebrities and media figures in his “Who’s Attacking Me Now?” segment, embraced extreme positions, and airily dismissed facts because, as he once put it, “reality has a well-known liberal bias.” But Colbert refrained from knowing winks to the audience. He knew not to spoil the joke.

Throughout it all, Colbert inhabited his invented character as deeply as Bryan Cranston did with Walter White, or James Gandolfini with Tony Soprano. Yet to fully grasp the Colbert phenomenon, you had to burrow down still another layer, to the sincerity quietly lurking beneath the noisily ironic stance. It became clear over the years how much Colbert actually cared about the stuff — call it democracy, for lack of a better word — that he enfolded within his elaborate burlesque.

One manifestation of that was the “Better Know a District” series, in which the host would interview members of Congress.

Last week, for the final “Better Know a District,” Colbert interviewed Representative Jack Kingston, Republican of Georgia, who had been the first guest on the segment back in 2005. “I’m leaving my show because I won television,” Colbert deadpanned to Kingston.

Yes, Stephen, you sort of did.