Not all celebrities get along like peanut butter and jelly, milk and cookies, Taylor Swift and Selena Gomez.
Over the past few years, feuds have broken out in Hollywood over mental health issues; late night talk show skits; and Kim Kardashian sex tape parodies.
Who won each of these rivalries? The public, really. They were darn entertaining!
Click around below to relive the back-and-forth between Kathy and Dami, David and Bristol, Kanye and Kimmel and many other famous folks who simply don't see eye-to-eye:
1. Seth Rogen vs. Nancy Grace
Nancy Grace wondered aloud on Twitter whether pot was to blame for a guy killing his wife. Seth Rogen replied that the anchor is a "dumbass."
2. Kathy Griffin vs. Demi Lovato
Kathy Griffin thinks Demi Lovato is the biggest "douche" in Hollywood. Lovato's fans thin Griffin should shut the eff up.
3. Lady Gaga vs. Perez Hilton
Lady Gaga has accused Perez of stalking her. Perez has slammed the singer for thinking she's the Queen of Twitter. Ugly stuff, people.
4. Khloe Kardashian vs. Joan Rivers
So much for Khloe's appearance on E!'s Fashion Police. The reality star snubbed the talk show host after Rivers mocked Kim Kardashian Superstar.
5. Selena Gomez vs. Lorde
Lorde doesn't think Selena represents feminists very well. When you're ready come and get it? Come on, Lorde says!
6. Drake Bell vs. Justin Bieber
Drake Bell slams Justin Bieber at every opportunity. He even wants the singer deported to Canada!
7. Carol Alt vs. Kate Upton
Carol Alt does not see what the "hullabaloo" is around Kate Upton. We question her hindsight.
8. David Letterman vs. Bristol Palin
David Letter had a lot of fun at Bristol Palin's expense when the teenager was pregnant. Some thought he crossed a line.
9. Jimmy Kimmel vs. Kanye West
These two have sort of buried the hatred hatchet. But Kanye and Kimmel went at it over Twitter after the latter mocked the former.
10. Sinead O'Connor vs. Miley Cyrus
Yes, Sinead O'Connor is still around. And her feud with Miley Cyrus actually ignited some interesting points about mental health.
11. Donald Trump vs. Rosie O'Donnell
It started in 2009 when Trump referred to O'Donnell as a "pig." She then slammed his failed marriages. Juicy stuff all around.
13. Naya Rivera vs. Lea Michele
Glee stars Naya Rivera and Lea Michele are reportedly beefing.