Zomsemble is derived from...
1. Rob Zombie: filmmaker.
2. Ensemble: a group of actors a director picks for his/her film.
This term not only defines single project ensembles, it embodies ensembles of Rob Zombie's entire body of work as well.
Rob Zombie has an extremely keen casting ability for amazing, talented, and underrated actors in all of his films. Here are a few: Sid Haig, Bill Moseley, Malcolm McDowell, Sheri Moon Zombie, Danny Trejo, Ken Foree, Dee Wallace, Karen Black, William Forsythe, Brad Dourif, and many others.
Moe: Mr. Zombie has some of the best actors ever in his movies. His casting is... mind-blowing!
Waggs: Fuck yeah! The Zomsemble is completely killer.
Moe: I love his movies too.
Waggs: Oh... right. His movies are killer, too.