Blutraven

Syrio is in an episode of Black Books as well.

Jory Cassel and Margaery Tyrell are both in Rush

In Harry Brown, Davos Seaworth's nephew kills Michael Caine's best friend, Walder Frey, and Jorah Mormont's in charge of the police.

It is. Didn't read any of the first thread but Ripper Street is almost exclusively cast with GOT actors.