Peter Roth leaving Fox Entertainment Group -- Doug Herzog will step in as the new President

The way the networks keep changing entertainment presidents, they’re starting to make Yankees owner George Steinbrenner seem like a patient man. Mere weeks after NBC Entertainment president Warren Littlefield got the heave-ho, Fox Entertainment Group prez Peter Roth is being shown the door.

Talk of Roth’s demise had been circulating for some time. But with the bulk of the net’s fall shows either pulled (Costello, Living in Captivity, Holding the Baby), struggling (Brimstone), or outright abandoned (Hollyweird), Fox and parent company News Corp. topper Rupert Murdoch had seen enough.

Roth, 47, who oversaw the development of hits like Ally McBeal and King of the Hill (as well as The X-Files and The Practice while he was head of 20th Century Fox Television), plans to return to producing. Ironically, he leaves Fox with potentially strong mid-season series: Family Guy, Futurama (from Simpsons creator Matt Groening), and Eddie Murphy’s The PJs. These shows have a shot at improving the net’s numbers, which have been boosted by reality specials, the World Series, and theatricals such as The Lost World.

Replacing Roth will be Comedy Central prez Doug Herzog, 39, who is expected to start early next year. A veteran of cable — he was previously exec VP of programming at MTV — Herzog is credited with putting Comedy Central on the map with such shows as South Park, The Daily Show, Win Ben Stein’s Money, and Dr. Katz: Professional Therapist.

Herzog’s an interesting choice. Heading up a cable net doesn’t fully prepare an exec for a broadcast gig, but given this era of shrinking audiences, it may make sense to pick someone who has the chops to expand Fox’s range. ”Network TV isn’t getting the job done,” says one TV studio head. ”This hire is an effort to get off the beaten track.”

But Herzog knows he can’t get too crazy. ”As edgy and boundary pushing as I want to be, I need to attract a big audience,” he says. And though he won’t be taking South Park to Fox, he does plan to ”bring a year’s supply of cheesy poofs.”