A director populates his movies with actors he's friends with.
Needs More Examples Picture this: you are movie director Tee Roper. You had a few indie hits under your belt and gotten enough of a rep that you finally have your chance at a big Hollywood production. And lo and behold, it was a success! You have finally hit the big time! You now have the chance to hire some big-name actors for your productions, sweet! And then something interesting happens: you and the actors you've hired start getting along well. Real well. You simply just click with them and you enjoy the collaboration. The actors approach you and say "Hey, Tee? Any time you need someone for a flick, gimme a call, buddy, I'll be there." And lo and behold, they are. You announce you're gonna make a new film and they are more than willing to star in it, maybe even approaching you themselves offering to act in it. Pretty soon, you and those particular actors become practically synonymous with each other. And that, my friends, is Buddy Casting: the tendency for directors to have a favored group of actors who concurrently star in their movies. This cannot happen without the director and actor getting along, as no matter how awesome the finished film is, they won't want to do another one if they hate each other's guts. The director and his stable of actors collaborate frequently because they like each other and believe they play to each other's strengths. Another form of buddy casting is that the director and actors were friends before their respective careers, and maybe hit the big time together at the same time. Perhaps even on the same movie. This doesn't mean that this is always a good thing, mind you. It sometimes happens that the director and actors become too associated to each other, to the point that they collaborate with each other in pretty much every flick they do, whether it merits it or not. The director will start cramming his buddy actors into his films even if it's a cameo which has no bearing on the plot, or give him a starring role for which his buddy actor is not an appropriate fit. On the actor's side, he starts starring in his buddy director's films so often, he starts getting pigeonholed into them. On a worst case scenario, the director gets criticized as being too dependent on his buddy actors, and the actors get basically blacklisted from other directors' productions to the point they ONLY get work from their buddy director. Compare/contrast Pigeonholed Director, Type Casting, Stunt Casting.