There was a massive casting update for The Twilight Saga: Breaking Dawn today as it was announced on the Twilight Facebook account that all of the vampire covens that appear in the last half of Breaking Dawn have been cast.
The Irish Coven Marlane Barnes as Maggie, Lisa Howard as Siobhan, and Patrick Brennan as Liam. There are way too many Lisa Howards and Patrick Brennans on IMDB for me to decide which one was actually cast. As soon as I can find out, I will post IMDB links and pictures.
The Romanian Coven has Noel Fisher as Vladimir and Guri Weinberg as Stefan. The Romanian Coven is the coven I was most interested in since they are both pretty ancient, like the Volturri. You may recognize Noel Fisher from Law and Order: SVU and Law and Order: Criminal Intent.
The American vampire nomads do not specifically belong to any coven. Lee Pace plays Garrett. He has long been rumored to have gotten that part. Now it is official. Toni Trucks plays Mary. Bill Tangrandi plays Randall. Vampire mates Peter and Charlotte are played by Erik Odom and Valorie Curry.
The only European nomad making an appearance in Breaking Dawn is Alistair who is played by Joe Anderson.
As you can see, there is probably only one actor, Lee Pace, that the general movie-going public may recognize. All the rest are relative unknowns with small parts in TV and films.
We are more than likely not going to see these actors and their characters until The Twilight Saga: Break Dawn Part 2 is in theatres, November 16, 2012.