*If will.i.am and Pharrell Williams were ever really friends, they aren’t now. It’s all because they’re suing each other over intellectual property rights.

The latest is that will.i.am has responded to Pharrell in a lawsuit, claiming Pharrell is basically a serial thief who steals names for profit — including Will’s.

An example, will cites is Pharrell’s YouTube channel called “I AM OTHER.”  After will.i.am fired off a cease and desist letter, demanding that Pharrell stop using “I AM,” Pharrell filed a lawsuit, asking a judge to protect his right to use the “I AM” moniker.

Now TMZ has obtained new legal docs, in which Will.i.am is countersuing Pharrell, claiming the dude has a long, copycat history.  Will.i.am notes … Pharrell co-founded a record label called Star Trak Entertainment — sound familiar?

But wait, there’s more.  Will also notes Pharrell is being sued by Marvin Gaye’s family for allegedly ripping off “Got to Give it Up” for his summer smash “Blurred Lines.”

And there’s still more.  Will claims Pharrell also tried to register the trademark, Pink Slime — which Will says is similar to Slime, owned by Mattel.  That’s a stretch, right?
As for using “I AM,” Will points out it will confuse people because they’re both on the same record label and they have similar musical styles.

It simple as far as will.i.am is concerned, if Pharrell wants to play, he’s got to pay.