Ulf Johannson, one of the seven-strong team whose reel includes Reebok "belly", has resigned after 12 years to direct on his own. He is setting up with the ex-Partizan producer Phillipa Smith.
Partizan's founder Georges Bermann, who represents Traktor, said: "He wants to develop his personal work."
Traktor, which comprises five directors and two producers, has won awards for work for Diesel, MTV and Malibu.
Traktor said: "Some people have commented that if Traktor are the Seven Dwarves, then Grumpy has left.
"We don't agree. Ulf is a great guy and an intuitively talented director.
We wish him luck on his new expedition. As our favourite, Cat Stevens, would sing: 'If you wanna leave, take good care. I hope you have a lot of nice things to wear. But then a lot of nice things turn bad out there. Oh baby it's a wild world.'"