Jan. 21, 2009 -- The mud is flying on late-night television these days.
Even David Letterman, no friend of NBC, is chiming in.
And plenty of other television personalities have piped in as well.
With so much mud flying, ABCNews.com thought it would be useful to have a primer on who said what. Below, late night's mudslinging match:
Rosie O'Donnell on Leno
O'Donnell blames Leno for pushing O'Brien from his "Tonight Show" perch.
"It was a really crappy move on Leno's part," O'Donnell told Us Weekly. "It was kind of career defining."
"Conan moved his family across the country and his entire staff to get a shot at what he worked 17 years for only to get it taken away by the bully on the playground who doesn't want to let go," she said.
O'Donnell compared Leno to Jeff Gillooly, who, along with wife figure skater Tonya Harding, orchestrated an assault on rival figure skater Nancy Kerrigan.
"At least Jeff Gillooly took a pipe and [admitted] he did it," O'Donnell said. "He didn't do it and go (imitating Jay Leno's voice), 'I don't know who hit her.' Gee, it was you, you're the one who hit her right in the knee, you know?"
Jon Stewart on Jeff Zucker
Stewart blamed NBC Universal chief Jeff Zucker for the late night brouhaha.
"He's the Cheney of television," Stewart said referring to former Vice President Dick Cheney, "just shooting shows in the face."
Letterman on Leno
After Leno told his audience Monday night that he had "no animosity" toward O'Brien and that the "Tonight Show" host was essentially not to blame in the late night debacle, Letterman decided to enter the fracas.
On Tuesday night, he ripped into Leno, calling him a "phony" who steals bits from other talk show hosts.
"Last night, Jay gave his state of the network speech, and he said that we should not blame Conan for what's going on. And I said to myself, 'No one is blaming Conan.'"
Letterman blamed Leno for not stepping aside the way Letterman did the last time the "Tonight Show" changed hands.
"Five years ago when NBC said to Jay, 'You know what, Conan is going to take over your job in five years.' That's when you say, 'OK, fine no hard feelings,'" Letterman said. "You call ABC. You call Fox. You try to get my job. But you leave."
"It's just part of evolution. You get fired and get another gig. Don't hang around waiting for somebody to drop dead," he joked.
Leno on Letterman
Leno fired back at Letterman Wednesday night, with a blow that may have been below the belt.
During his monologue, Leno told the crowd and band leader Kevin Eubanks that "Letterman has been hammering me every night."
Turning to Eubanks, he continued, "Hey Kev, you know the best way to get Letterman to ignore you? Marry him. He will not bother you. He won't look you in the eye."
Dick Ebersol on O'Brien
Ebersol, the chairman of NBC Universal Sports, came to Leno's defense, saying the reason for his return to late night came down to one thing: poor ratings for O'Brien's "Tonight Show."
"What this is really all about is an astounding failure by Conan," said Ebersol, a frequent consultant on changes to NBC's late-night lineup.
Referring to jabs made by O'Brien and Letterman, Ebersol said it was "chicken-hearted and gutless to blame a guy you couldn't beat in the ratings."
Jennifer Lopez on O'Brien, Leno and Letterman
J-Lo pulled no punches when she appeared on George Lopez's new TBS show Monday night, taking swipes at all three late-night hosts.
Acting as a "guest host" on "Lopez Tonight," J-Lo opened the show with: "Welcome to 'Lopez Tonight,' where nobody gets fired, they just get replaced by a bigger star with the same last name..."
She joked that a Manhattan bartender has created a drink in O'Brien's honor: "It's called The Go-Back-To-Manhattan...it's a Manhattan with sour grapes and a knife in it."
Then she wondered if Leno was too old to attract young, hip viewers. "NBC is thinking about changing the NBC peacock to a cougar, since they are trying to attract young people to an old host," she joked.
"Some women don't like the expression 'Cougar' but it's better than what guys get, right? An older guy who dates a younger girl that's called a 'Letterman'," she quipped, referring to Letterman's confession last fall that he had affairs with staff members.
O'Brien on Leno
After announcing that he would not continue hosting the "Tonight Show" if it was moved to 12:05, O'Brien took a swipe at the man who hosted before him.
"Hosting the 'Tonight Show' has been the fulfillment of a lifelong dream for me, and I just want to say to the kids out there watching: You can do anything you want in life. Unless Jay Leno wants to do it, too."
Jimmy Kimmel on Leno
ABC's late night host didn't hold back when he guest-ed on Leno's show Jan. 14.
Kimmel participated in Leno's "10 at 10" question-and-answer segment via satellite. Asked by Leno, "Ever order anything off the TV?," Kimmel shot back, "Like NBC ordered your show off the TV?"
Kimmel continued the zingers and ended the interview admonishing Leno, saying, "All you have to take care of is cars. I mean, we have lives to lead here. You have $800 million dollars -- for God's sake, leave our shows alone."
Norm Macdonald On O'Brien
Guesting on O'Brien's show Jan. 19, "Saturday Night Live" alum Norm Macdonald arrived with gargantuan gift basket and kind, if belated, words for his old friend.
Reading a card he supposedly wrote seven months ago, Macdonald unabashedly declared O'Brien "the new king of late night," even as everyone knew his show was slipping away.
Jerry Seinfeld on Leno
Jerry Seinfeld stood up for Leno and NBC – the network that, coincidentally, broadcast his hit sitcom and plans to air his new reality show, "The Marriage Ref" – from the start of the whole late night brouhaha.
On Jan. 10, Seinfeld praised NBC's vision in moving Leno to prime time, even if the gamble didn't quite work out as planned.
"This was the right idea at the wrong time," Seinfeld said while promoting his new show. "I'm proud that NBC had the guts to try something."
Seinfeld also said O'Brien will emerge from the wreckage unscathed, but said O'Brien has only himself to blame.
"What did the network do to him?" Seinfeld asked. "I don't think anyone's preventing people from watching Conan. Once they give you the cameras, it's on you. I can't blame NBC for having to move things around. I hope Conan stays, I think he's terrific. But there's no rules in show business, there's no refs."