It's easy to forget that the people who are featured in our favorite movies and TV shows are actors who have entirely different personalities in real life. More often than not, actors fail to see eye to eye with some of their fellow actors for the entire duration of their contracts. As viewers, we only get to see the final product, which can be a good thing considering that no one wants to watch on-screen besties throw insults back and forth.

Directors and producers have their hands full when it comes to keeping their actors in check. While some might start as best friends (or actors who enjoy working together), things can change pretty quickly. The following actors were supposed to be chummy both on and off the screen. But let's face it, that just didn't happen. These co-stars hate each other in real life, no matter how close their characters are on TV.

15 Lost: Dominic Monaghan Wasn't A Fan Of Matthew Fox

Back in 2012, former Lost co-stars Dominic Monaghan and Matthew Fox battled it out on Twitter, putting an end to their wavering friendship. Dominic could not believe that Matthew had attacked a female bus driver the previous year. When a fan asked Dominic to invite Matthew to Twitter, he replied: "He beats women. No thanks."

14 Will & Grace: Debra Messing & Megan Mullally Clashed On Set

Megan Mullally and Debra Messing from Will & Grace aren't known for getting along on set. After a huge and secretive fight, Megan stopped following Debra on Instagram, and she did the same with Sean Hayes. Megan and Debra kept their distance from each other while promoting the eleventh season of the show.

13 The Vampire Diaries: Nina Dobrev & Paul Wesley Used To Be Enemies

Nina Dobrev and Paul Wesley might have appeared like the perfect friends and lovers while on the set of Vampire Diaries.  But these two didn't always get along. They feuded for the first few seasons before letting bygones be bygones. Their personalities immediately clashed. But soon enough, they became like family and have maintained a good friendship.

12 Sex And The City: Kim Cattrall & Sarah Jessica Parker Were The Opposite Of Chummy

You would think that Kim Cattrall and Sarah Jessica Parker from Sex And The City would be just as close in real life as they are on the screen. But that just isn't the case. Kim and Sarah hate each other with a passion. Their personalities clash and Kim could never get over Sarah's huge paycheck and ego.

11 Gilmore Girls: Lauren Graham & Scott Patterson's On-Screen Chemistry Doesn't Reflect Their Real-Life Situation

At first glance, Lauren Graham and Scott Patterson from Gilmore Girls seem like the best on-screen friends and lovers. But, if you take a closer look, you'll realize that these co-stars have little love for each other. Lauren firmly denied that she and Scott were close in real life when asked by a reporter.

10 Sam & Cat: Ariana Grande & Jennette McCurdy Never Patched Things Up

Ariana Grande and Jennette McCurdy used to be close friends and co-stars while on the set of Sam & Cat. However, these ladies had their fair share of beef. Jennette was angry because Ariana got paid a lot more than her. Plus, Jennette's risky photos were leaked on the internet, and Ariana refused to attend an award ceremony with her.

9 What Not To Wear: Stacy London & Clinton Kelly Are Not As Close As They Seem

Stacy London and Clinton Kelly have been close friends for decades. They came up together on What Not To Wear and have supported each other for years. But in 2018, a feud broke out between them, causing Stacy to block Clinton on Twitter. Clinton said that Stacy's block was like a "slap in the face."

8 Grey's Anatomy: A Fight Between Patrick Dempsey And Isaiah Washington Got Physical

It's no secret that the cast of Grey's Anatomy did not get along with Isaiah Washington. Isaiah and Patrick Dempsey got into a physical altercation while on the set of the show. Isaiah got "all in Patrick's face" because he was late for work, going as far as to grab him by the throat.

Related: 15 Questions We Need Grey’s Anatomy To Answer Before The Finale

7 The Good Wife: Julianna Margulies & Archie Panjabi Couldn't Even Share A Set

Julianna Margulies and Archie Panjabi from The Good Wife used to be a match made in heaven. But their clashing personalities could not be tolerated, leading to Archie being written off the show. Little is known about what actually went down, but Julianna and Archie hated each other so much they refused to share a set.

6 Glee: Naya Rivera & Lea Michele Never Became Friends

We wouldn't go as far as to label Naya Rivera and Lea Michele's characters on Glee as close. However, they did share special moments that made fans view them as friends instead of enemies. But in real life, Naya and Lea just couldn't stand each other. Their personalities clashed big-time.

Related: 15 BTS Pics Of Lea Michele And The Rest Of The Glee Cast

5 Victorious: After Years, Ariana Grande & Victoria Justice Still Hate Each Other

Ariana Grande and Victoria Justice both came up together on the Nickelodeon show Victorious. Victoria once referred to Ariana as a "scene-stealer." And Ariana never invited Victoria to star in her music video, "Thank U, Next" like she did with the rest of the cast. These two ladies just couldn't form a proper friendship.

4 Charmed: Shannen Doherty & Alyssa Milano Couldn't Stand Each Other

This next feud is one of the oldest in Hollywood. Alyssa Milano and Shannen Doherty used to star on Charmed. However, despite being on-screen besties, these ladies could not stop themselves from bumping heads. Luckily, Alyssa and Shannen have finally buried the hatchet, decades after Charmed came to an end.

Related: State Farm Claims Shannen Doherty Is Using Her Cancer Battle To Gain Sympathy

3 Gossip Girl: Blake Lively & Leighton Meester Constantly Feuded

Blake Lively and Leighton Meester are well-known for playing on-screen besties and rivals on Gossip Girl. However, these actors were closer to enemies than besties in real life. Turns out, Blake and Leighton had very different personalities. But instead of feuding around the clock, they pretended to be close for their fans.

2 Desperate Housewives: Almost Everyone Hated Teri Hatcher

And the award for the most dramatic TV show of all time goes to... Desperate Housewives! It's no secret that the cast fought tooth and nail throughout the series' run. However, did you know that Teri Hatcher was usually the one to blame for the show's dramatic moments? It seems like everyone had a bone to pick with Teri.

1 The Hills: Heidi Montag & Lauren Conrad Want To Put Their Friendship Behind Them

If you were a fan of The Hills, you were most likely shocked when Lauren Conrad and Heidi Montag cut their friendship short and became public enemies. According to Lauren, Heidi "knows what she did." These on-screen besties took out their claws when rumors of a scandalous tape made headlines.

Next: 15 Disney Stars Who Couldn’t Stand Working With Each Other