These TV co-star tandems came from different genres and eras, but all reportedly - or very openly, in some cases - hated one another.
From coming to physical blows to keeping their distance to the point where CGI had to bring them together on film, their tension was palpable.
We're talking problems, no idea how to solve 'em, and serious bad blood (hey!). See which feuds you recall and which you had no idea about ...
Patrick Dempsey and Isaiah Washington
Isaiah Washington got fired from Grey's Anatomy for homophobic slurs that ultimately outed T.R. Knight, but what a lot of people forget is that he made them during a PHYSICAL FIGHT with Patrick Dempsey.
Julianna Margulies and Archie Panjabi
Emmy winners Julianna Margulies and Archie Panjabi of The Good Wife REALLY don't get along ... to the point where they did not share physical space together in two YEARS. In Panjabi's final episode, the one scene the feuding pair did share was made possible only with CGI magic. Insane.
Marcia Cross and Teri Hatcher
Marcia Cross and Teri Hatcher of Desperate Housewives fame engaged in some petty, Desperate Housewives-esque drama themselves, most notably when Cross "lost it" over Hatcher being moved into the center of the group shot for a Vanity Fair spread and getting more PR then the rest of the cast. Seriously.
Jennie Garth and Shannen Doherty
Jennie Garth confirmed rumors of a feud with her Beverly Hills 90210 costar Shannen Doherty, admitting they "wanted to claw each other's eyes out." Rumors of similar issues with Doherty followed her to Charmed, as well, so we're guessing she could be a handful on set. On a total side note, wonder what reality show Tori Spelling is filming these days.
Sophia Bush and Chad Michael Murray
"My mother once said to me that if you don't have anything nice to say, not to say anything at all." - Sophia Bush's actual quote about Chad Michael Murray her One Tree Hill co-star for nine seasons. (This was after they got married and then divorced just a couple of months later.)
Jennette McCurdy and Ariana Grande
Jennette McCurdy and Ariana Grande starred on the Nickelodeon hit Sam & Cat, which was abruptly canceled after its first (and only) successful season amid rumors of tension, back-stabbing and cat-fighting between the young stars.
Nina Dobrev and Ian Somerhalder
Maybe this one is a bit of a stretch, but once Nina Dobrev and Ian Somerhalder broke up in real life, The Vampire Diaries went into a creative tailspin that saw their characters spending less and less time together until Dobrev ultimately left the show. Meanwhile, Ian engaged in a very public, whirlwind courtship and marriage with their former mutual friend Nikki Reed. Possibly all a coincidence, but we doubt it.
Balthazar Getty and the Brothers & Sisters Cast
Balthazar Getty became an outcast among his TV Brothers & Sisters on ABC after he allegedly made staff members cry ... and cheated on his wife, to whom many of his co-stars had become close, with Sienna Miller.
David Duchovny and Gillian Anderson
Over nine seasons as Mulder and Scully, The X-Files' David Duchovny and Gillian Anderson reportedly got tired of each other and then some. However, they're now coming back together for Fox's reboot, and Duchovny was quoted as saying, "We've forgotten why we hate one another and can only remember why we love one another." All's well that ends well.
Sarah Jessica Parker and Kim Cattrall
The New York tabloids had a field day with rumors of Sarah Jessica Parker and Kim Cattrall squabbling on and off the set of Sex and the City. Usually the feud is "allegedly" over money, though all parties denied any in-fighting publicly.
Charlie Sheen and Everyone He Has Ever Worked With
Do we even need to explain?