If snarky commentary could deep-fry, Jay Leno would be onion rings. Ever since NBC announced that Jay Leno's current 10pm show would be fine-tuned and moved to the 11:35 time slot, the knives have been out for the former Tonight Show host. Is Leno a hapless pawn caught in the middle of cutthroat NBC politics? Or is he a master manipulator, pulling strings and calling in favors in an attempt to save face? The true story remains to be seen, but this isn't the first time that personalities clashed and venom was spewed in the world of late night television.

1. Jack Paar vs. NBC

jack-paarJack Paar took over hosting duties of The Tonight Show in 1957. He transformed the show from its typical variety format to something edgier and more unpredictable: He not only had the most popular performers of the day on his couch, he also interviewed non-entertainers like Billy Graham and Richard Nixon. He went to Cuba to talk to Fidel Castro, and broadcast live from Germany when the Berlin Wall was being built. As controversial as some of those shows were at the time, they were still aired unedited. The proverbial straw that caused the camel to cross that fine line with NBC censors was a joke Paar related during his monologue on February 10, 1960.

It was a four-minute story that involved the misunderstanding when a British tourist in Switzerland inquired about the "W.C." (meaning the water closet, or toilet) and receiving directions to Wayside Chapel in response. Communist regimes and fascist dictators were more acceptable than bathroom humor in those days, and NBC excised Paar's monologue without consulting him. When he found out about it, he made a tearful announcement on the next evening's broadcast denouncing censorship: "I love NBC, and they've been wonderful to me. But they let me down." And then he abruptly walked off the set. Public outcry encouraged Paar to return to his hosting duties three weeks later; as he strolled casually onstage he looked into the camera and stated: "As I was saying before I was interrupted"¦"

2. Johnny Carson vs Jay Leno

In 1987, Johnny was still the host and head honcho of The Tonight Show, but Jay Leno was the exclusive "guest host" for those nights when Johnny was unable to work. When Carson eventually negotiated a shorter work week into his contract, it meant that Leno became the de facto host each Monday night. All was copacetic until late 1991, when Leno's management released stories to the press stating that Carson planned to retire the following year, and Leno would assume host duties of The Tonight Show. Johnny had been considering retirement, but those talks were still speculative and behind-the-scenes, and he felt that Jay Leno had forced his hand. Carson not-so-subtly let his true feelings be known by snubbing Leno's Tonight Show and appearing on The Late Show with David Letterman after his retirement.

3. Johnny Carson vs. Joan Rivers

Acerbic comedienne Joan Rivers got her first big break on The Tonight Show, and she and Johnny became friendly enough over the years that he anointed her "permanent guest host" in 1983. Rivers filled in for Johnny for the next three years to great acclaim. In 1986, executives from the fledgling Fox network offered Rivers her own late-night talk show. Carson, who'd been something of a mentor to Rivers over the years, felt betrayed because she did not advise him in advance of her decision—he first learned of her upcoming show via a televised press conference. The Late Show Starring Joan Rivers was cancelled less than a year after it debuted, and Johnny Carson never spoke to Rivers again.

4. Arsenio Hall vs. Jay Leno

leno-hallThe Arsenio Hall Show debuted in 1989 and was an immediate ratings sensation. He appealed to a younger, hipper audience than other talk shows did at the time. (You'd never see Tupac Shakur sharing the sofa with Don Rickles on Arsenio.) When it was announced that Jay Leno was taking over the reins of The Tonight Show, Hall was undaunted; he bragged in a magazine interview that he'd kick Leno's (backside). Unfortunately, Arsenio suffered from the "too hot, too soon" syndrome, and Arsenio's schtick eventually became dated. People stopped "woofing" and circling their fists, and hip-hop took a temporary back seat to the grunge movement. Viewers drifted to Letterman and Leno, who were also hosting younger and more contemporary artists as guests. Arsenio's show was cancelled in 1994, but he eventually mended his fences with Leno and made several appearances on The Tonight Show.

5. David Letterman vs. Jay Leno

Had Johnny Carson any say in the matter, his Tonight Show successor would have been David Letterman. But NBC decided that Jay Leno was the heir apparent, and a disgusted Dave jumped to CBS in revenge. Late Night with David Letterman had been airing at 12:30am on NBC, right after The Tonight Show, for 10 years, so when CBS offered him an 11:30 time slot in direct competition with Jay Leno, he couldn't refuse. The Tonight Show garnered higher ratings, but The Late Show with David Letterman had a younger, more appealing demographic for advertisers. Even though Leno has very publicly attempted to end the feud (revealing, for example, to an interviewer that he'd sent a card to Letterman after his bypass surgery), the two still have their own version of the Berlin Wall between them.