NEW YORK — “Saturday Night Live,” which has never shied from self-congratulation with countless best-of, holiday and anniversary shindigs, is doing it again, big-time.

“The SNL 40th Anniversary Special,” three hours of it, will air live at 8 p.m. Sunday on NBC.

Everyone who has ever been an “SNL” regular, guest host, musical guest or behind-the-scenes creative force has been invited. Indeed, it seems every boldface name who ever tuned in to watch might be showing up at fabled Studio 8H. Attendees announced so far range from Dan Aykroyd, Alec Baldwin and Robert De Niro to Kanye West, Betty White and Kristen Wiig. And to welcome them all, the “Today” show anchor team will host “The SNL 40th Red Carpet Live” at 7 p.m.

“We waited to see who RSVPed, then we started thinking about what we could do with the people we knew were coming,” said Lorne Michaels last week. “We’re still working on it, as more people reply.”

The show will include sketches and other comedy bits employing what Michaels calls “a mash-up of different generations, so you’ll see people working with people they never actually worked with” as “SNL” regulars.