2011 Celebrity Feuds: Whose Side Are You On?

Not everybody got along in 2011.

Kelly Osbourne famously dissed Christina Aguilera for putting on a few extra pounds, joking that she became "the fat bitch she was born to be."

PHOTOS: 2011 CELEBRITY FEUDS: WHOSE SIDE ARE YOU ON?

Why the hate? "She called me fat for so many f-cking years," Osbourne explained on E!'s Fashion Police. "So you know what? F-ck you! You're fat too."

PHOTOS: Kelly Osbourne's body through the years

The blonde stars weren't the only ones who butted head this year. Maksim Chmerkovskiy trash-talked fellow Dancing With the Stars pro Derek Hough on Good Morning America. He further alienated himself from the DWTS judges when he called the ABC series "my show."

VIDEO: Why Maks really lashed out at judge Len Goodman

Maroon 5's lead singer Adam Levine waged war on MTV during the Video Music Awards, saying it was the "one day a year" when the network "pretends to still care about music. Meanwhile, Glee co-creator Ryan Murphy called Kings of Leon "self-centered a--holes" for not allowing their music to be featured on the Fox hit.

For more outrageous celebrity feuds, click through the gallery and vote for which star came out on top in 2011.