I have noticed that whenever an actor from TP is in a show/movie, there is almost always another actor from TP in the same show/movie! I find this very fascinating. I have seen this on many occasions. for example:

Miracle - Don Davis(Major Briggs) and Kenneth Welsh(Windom Earle)
Robocop - Dan O'Herlihy(Andrew Packard) and Miguel Ferrer(Albert Rosenfield)
Seinfeld Episode "The Wizard" - Don Davis(Major Briggs) and Grace Zabriske(Sarah Palmer)
Sherilyn Fenn in "The United StateS of Leland" (ok, this one is a stretch)

It's amazing that the duality so prevalant in the show has been carried on by the actors outside of the show. I keep seeing this all the time. Has anyone else noticed this? i'll post more examples as I think of them.

The People Under the Stairs -- Everett McGill (Big Ed) and Wendy Robie (Nadine)

Thunder Point -- Kyle MacLachlan (Coop)  and Kenneth Welsh (Windom Earle)

Dune -- Kyle MacLachlan and Everett McGill--AND Jack Nance--(Pete)

Blue Velvet -- Kyle and Jack Nance

Welcome, Maggit!! :D

Actually Sherilyn's character exited the show during season 5 and Dana's character join the show in season 6.

Please don't ask how I know. Just trust in the fact that I took one for the team. :P

There's one episode of Seinfeld with Frances Bay and Walter Olkewicz.
Then there's a Seinfeld episode with Don Amendolia, Frances Bay, Grace Zabriskie, and Warren Frost.

Don't forget West Side Story with Russ Tamblyn and Richard Beymer.

Here's a few others:

The Hidden (Kyle MacLachlan and Chris Mulkey)

Harry Dean Stanton and Grace Zabriskie were both in Big Love.

And if we're counting Lynch movies, Sheryl Lee, Sherilyn Fenn, Grace Zabriskie, Harry Dean Stanton, David Patrick Kelly (Jerry Horne), Frances Bay (Mrs. Tremond), Lisa Ann Cabasa (Jenny), Nicholas Love (Malcolm Sloane), and Ed Wright (Dell Mibbler) are all in Wild At Heart. Also Jack Nance and Charlotte Stewart (Betty Briggs) are both in Eraserhead, and Frances Bay is in Blue Velvet as well. Oh yeah, Ian Buchanan and Miguel Ferrer were in On the Air, and Harry Dean Stanton and Alicia Witt (Gursten Hayward) were both in Hotel Room (though not together) Also Ray Wise was in Robocop too... that's all I can think of for now.

Edit: Oh hey and Jurgen Prochnow (Woodsman) is also in Dune, as well as Alicia Witt...

Landspeed-
Billy Zane, Pamela Gidley, Ray Wise

The Willies-
Kimmy Robertson, Dana Ashbrook

A Few Good Men-
James Marshall, Kiefer Sutherland

Even Cowgirls Get the Blues and Drugstore Cowboy
Grace Zabriskie, Heather Graham

Liebstraum-
Pamela Gidley, Alicia Witt

Susan's Plan-
Billy Zane, Lara Flynn Boyle

Red Shoe Diaries 3, 4, 12:
David Duchovny, Sheryl Lee

This World, Then the Fireworks:
Sheryl Lee, Billy Zane

Zoolander:
David Duchovny, Billy Zane

Happiness:
Lara Flynn Boyle, Molly Shannon

Robocop-
Miguel Ferrer, Ray Wise

Desert Winds-
Grace Zabriskie, Heather Graham

Megaville-
Grace Zabriskie, Billy Zane, Al Strobel

Silver City-
Miguel Ferrer, Billy Zane

West Side Story-
Richard Beymer, Russ Tamblyn

Dream a Little Dream
Piper Laurie, Harry Dean Stanton

Chris Isaak Show 1-
Don Davis, Chris Isaak

X Files (several episodes)
Don Davis, David Duchovny

Hideaway-
Kenneth Welsh, Don Davis

In The Mouth of Madness-
Frances Bay, Jurgen Prochnow

Judge Dredd-
Jurgen Prochnow, Joan Chen

Brotherhood of Justice-
Kiefer Sutherland, Billy Zane

Chaplin-
Moira Kelly, David Duchovny 

Changing Habits-
Moira Kelly, Frances Bay 

Edit: Oh hey and Jurgen Prochnow (Woodsman) is also in Dune, as well as Alicia Witt...

So were Everett McGill, Jack Nance and David Patrick Kelly

Lynch's On the Air also had some Peaks actors, if I recall

The Straight Story has Harry Dean Stanton and Everett McGill 

Inland Empire has Grace Zabriskie and Harry Dean Stanton 

Wow, apparantly this is a known thing. I purposely excluded lynch movies, since that is pretty obvious. some of these are really good calls. I didn't necessarily mean some of the one-time, smaller parts like kiefer or molly shannon, but good points. I meant more of the permanent, reoccuring characters.

 What is it with these people following eachother around? i know there are many movies and such around, but I think it's amazing that these random people end up working together.

So were Everett McGill, Jack Nance and David Patrick Kelly

 Rocksandbottles already mentioned McGill and Jack Nance... I missed David Patrick Kelly though...

Well, after Twin Peaks those actors were in demand. Casting people hoped they would have a draw, but also knew if they cast multiple actors from the same show then their project would seem attached to TP, which could be beneficial or detrimental.  More often then not, TP actors don't appear together.   Check Twin Peaks on www.us.imdb.com

Totally forgot about The Hidden! Ha...I actually have that movie on DVD. :D

Another X-Files episode had Michael Horse (Hawk) and David Duchovny...there was one with Richard Beymer too...peeled his face clear off!! Oh! And the one with Michael J. Anderson...the circus one...Humbug or something...