Bill O'Reilly vs. Young Jeezy and Jay-Z
What's the Beef? The FOX host, along with Dennis Miller, slammed the two rappers over a song they performed during inauguration week called 'My President Is Black.'

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Bill O'Reilly vs. Jessica Alba
What's the Beef? The actress called the host "kind of an a--hole" when asked why she doesn't watch the show. As a result, Bill called her a "pinhead" for calling Sweden a neutral country, which it generally is.

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Bill O'Reilly vs. Keith Olbermann
What's the Beef? Olbermann frequently names "Bill-O" as the winner of his 'Worst Persons in the World' segment, which inspired the FOX host to start a petition drive to replace Olbermann with Phil Donahue. It didn't work, and Keith continues the feud nightly. O'Reilly refuses to say his rival's name on the air any more.

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Bill O'Reilly vs. Rosie O'Donnell
What's the Beef? Back when she was on 'The View,' Rosie got serious and insinuated that the capture of British sailors by the Iranian military was masterminded by the U.S. as a reason to justify a war on Iran. O'Reilly called Rosie "irresponsible" and "hateful," and called for ABC to terminate her contract.

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Bill O'Reilly vs. Al Franken
What's the Beef? The pair squared off in a debate back in 2001, where there was much shouting. Let's just say they've never liked each other. Watch a clip of the debate here.

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Bill O'Reilly vs. Ludacris
What's the Beef? When Pepsi hired the rapper as a spokesperson, the FOX host flipped his lid and called for an all-out boycott of the sugary soda. Pepsi caved and fired Cris the axe.

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Bill O'Reilly vs. San Francisco
What's the Beef?

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Bill O'Reilly vs. Nas
What's the Beef? When Nas announced he was staging a concert at Virginia Tech in the wake of the shootings there in 2007, O'Reilly called it an "abomination" and an "atrocity." Nas responded bluntly by labeling Bill a businessman whose "marketing plan is racism."

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Bill O'Reilly vs. George Clooney
What's the Beef?

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Bill O'Reilly vs. General Electric Co.
What's the Beef?

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Christina Aguilera is not only waving off talk that she's been borrowing Lady GaGa's look, she's even expressing doubts that GaGa is a lady at all. "I'm not quite sure who this person is, to be honest," Xtina told the LA Times. "I don't know if it is a man or a woman. I just wasn't sure."

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William Shatner has filmed two separate viral videos complaining that former 'Star Trek' crew mate George Takei failed to invite him to his September wedding. Takei had written of Shatner's on-set ego in his autobiography years ago.

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The feud between Samantha Ronson and Joe Francis started during a VMA party, when Francis approached Lohan and Ronson's table. Ronson recalls the evening, "He said hello to Lindsay and looked over at me as if I wasn't a human being. He's got no manners."

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Richard Dreyfuss bit the hand that fed him during a sit-down on "The View," attacking director Oliver Stone ("you can be a fascist, even when you're on the left") and dissects "W," in which he stars as Dick Cheney, as merely "6/8ths of a great film."

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The set of 'Ugly Betty' reportedly turned, well, ugly when tension between America Ferrera and guest star Lindsay Lohan boiled over. A Page Six report says the feud between the two got so bad, Lohan cut her six episode 'Betty' stint down to four.

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Andy Samberg's seemingly-harmless impression of him on 'Saturday Night Live' didn't sit well with Mark Wahlberg, who told the NY Post that "it wasn't like Tina Fey doing Sarah Palin, that's for sure." He went on to say he's turned down offers to host the late-night staple "a ton of the times" before appearing on 'SNL' to make fun of the entire episode.

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The war of fists between the Blonsky and Golden families has turned into a war of words, as Blonsky now says she is "completely destroyed" by their July airport brawl.

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Mischa Barton vs. Victoria Beckham: The actress has launched a one-woman, and ultimately one-sided, fashion battle with the extremely stylish Spice Girl. "Posh doesn't strike me as particularly stylish," she said. "I don't think she's a good example of British style at all."

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Dennis Quaid vs. Meg Ryan: The former husband and wife who divorced in 2001 are feuding again, as Ryan has said in multiple interviews that Quaid's infidelity caused her to have an affair.

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Pat O'Brien vs. Lara Spencer : Pat O'Brien, former host and current correspondent of 'The Insider' wrote an email to staffers this weekend, slamming his colleague Lara Spencer. He suggested Spencer's most popular work "makes the viewers want to vomit." Nice.

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