It looks like there's a battle of Katy Perry's ex vs. Donald Trump as the latest celebrity feud.

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Perry's ex-husband Russell Brand made a few appearances lately on shows like NBC's Today, ABC's The View and CBS' Entertainment Tonight, which business man Trump apparently watched since he had a lot to say about it.

Trump took to Twitter on Thursday to not only insult Brand, but also questioned what Perry saw in him since the two used to be married.

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".@katyperry Katy, what the hell were you thinking when you married loser Russell Brand. There is a guy who has got nothing going, a waste!" Trump wrote.

Right after this, he tweeted, ".@katyperry I watched Russell Brand and I think his mind is fried - he looks really bad. Russell is a total joke, a dummy who is lost!"

But he didn't stop there. The Celebrity Apprentice host even took to Instagram to post a video of himself saying nasty things about Brand. On Friday, the video was posted that shows Trump saying, "I watched Russell Brand on television the other night. What the hell was Katy Perry thinking when she married this guy? What a loser he is."

Oh, there's still more.

On Friday, Piers Morgan posted a story from Daily Mail on his thoughts on the feud, which Trump responded to.

".@piersmorgan Russell has nothing going for himself except for energy and aggression. Without that he would be dead-a first class dummy," Trump wrote.

Brand responded to these tweets on Thursday when he wrote, ".@realDonaldTrump are you drunk when you write these tweets? Or does that foam you spray on your bald head make you high?"

Perry has not responded to the feud.