Is there a grand unifying theory behind all these actors appearing in the same films?

What’s the common bond? I’m talking about the fact that (and here’s a sort of off-the-cuff partial list) Judd Apatow (director), Seth Rogen, Elizabeth Banks, Steve Carrell, Will Ferrell, Paul Rudd, Jane Lynch, Jonah Hill, Joe Lo Truglio, Bill Hader, James Franco, and a few others on the fringe all seem to be appearing in the same films, regardless of who is writing and directing. This sort of came to a head recently where Pineapple Express (dir. David Gorgon Green), Zak and Miri Make a Porno (dir. Kevin Smith), and Role Models (dir. David Wain) practically have the same cast starring in all three films, out (roughly) at the same time.

Is there some sort of grand, unifying “brat pack”-esque name for this trend?

“wanting to not screw it up?”

Somebody’s given you a budget of $10 million. You take a gamble and make a movie with a given set of people you’ve never worked with before. It’s a huge success.

Somebody gives you another $10 million and says “make another movie.”

You can:

(a) gamble the second $10 million on an entirely new set of people
(b) work with people you know can make a huge success.

Sort of, but not really. There seem to be three competing, but occasionally overlapping troupes:

The Frat Pack (common bond: the actors themselves): Will Ferrell, John C. Reilly, Ben Stiller, Owen Wilson, Vince Vaughn, Luke Wilson, Paul Rudd and Steve Carell

The Judd Apatow Players (common bond: Apatow directs or produces): Seth Rogen, Jonah Hill, Paul Rudd, Jason Segel , Jay Baruchel, James Franco, Bill Hader, Steve Carell

Kevin Smith’s Regulars (common bond: Kevin Smith directs): Ben Affleck, Jason Lee, Matt Damon, Kevin Smith, Jason Mewes, Joey Lauren Adams, Jeff Anderson, Brian O’Halloran, Ethan Suplee, George Carlin (RIP), Chris Rock, Alanis Morissette

Free Agents: Elizabeth Banks and Sean William Scott, who have appeared in movies from all three groups.

With the exception of ‘Zack and Miri Make a Porno’, all those movies are either written, produced or directed by Apatow.

The world of Kevin Smith’s movies is called the ‘View Askewniverse’. Common references throughout the films include locations in New Jersey, Jason Mewes and Kevin Smith as Jay & Silent Bob, the ficticious ‘Mooby’s’ fast food restaurant and Matt Damon, Ben Afleck and Jason Lee as multiple characters.
Will Farrell has also appeared in movies from all three troops (Old School, Anchorman and Jay & Silent Bob Strike Back).

What about Justin Long?

Judd Apatow has said (somewhat tongue-in-cheek) that he feels obligated to keep these guys employed, since he got them into the business in the first place. Rogen, Franco, Segel, and Baruchel, Martin Starr, and Samm Levine were around for Apatow’s Freaks & Geeks and Undeclared years, and I’m sure they’re all pretty comfortable with each other.

Personally, I like seeing all these guys pop up in current (and more importantly, good) movies.