M.I.A.
Conceited and jealous of the commercially superior girls.
Madonna
She's a bitch, but I love her for it.
Mariah Carey
The epitome of a "diva" in only the worst sense of the word.
Kristen Stewart
I can only imagine she's eternally grumpy because she's so average, not only in terms of her appearance, but also in terms of her talent.
Taylor Momsen
Read one of her ridiculous interviews...
Love that the Christina stans immediately mentioned her and did our dirty work for us.
Elly Jackson of La Roux, because she never has any respect for other singers (e.g. accusing Taylor Swift of being a "manufactured pop princess") or any type of music (e.g. R&B as boring and pointless) and she thinks she's superior to everybody else, which smacks of absolute arrogance.
But really, she's a miserable and worthless excuse for an artist and she shouldn't have any right to constantly criticize other artists.
DEATH at the amount of Aguilera shade there is on this board. I used to be a big fan of her's and even consider Stripped amongst one of my all-time favorite pop albums, but I'm glad she's getting fed a little of piece of humble pie right now. This era is going to be just awful
Anyway, in terms of arrogant celebs ... I'm obviously saying Christina and Kanye ... There's others that come to mind but those are the two that stick out. GaGa comes off as being a little prententious to me as well (though she has every single right to be right now)
and they say Britney's the ****ty one 
I used to be a big fan of her's and even consider Stripped amongst one of my all-time favorite pop albums, but I'm glad she's getting fed a little of piece of humble pie right now. This era is going to be just awful 