John Frank Levey, CSA was, with Melanie Burgess, in charge of casting Torchwood: Miracle Day.
Levey is one of the most award-winning casting directors in American television history, having completely dominated the Emmy Awards from 1995 to 2001 by winning four statuettes in that period. He has also been recognised by the Casting Society of America on multiple occasions since 1989.
He is particularly well-known for his casting of The West Wing and ER; in 2000 he actually received Emmy nominations for both shows, and won for The West Wing. His guild has of course recognised him with an Artios for those two NBC dramas, but they've also nominated his work on Third Watch, China Beach and Southland.
He and Burgess have long worked together, though they do not completely share the same resumé. For instance, she did work with him on ER, for a time, but not on The West Wing.
Levey's work on ER could be said to have had an indirect impact on Doctor Who. Because he cast Alex Kingston in a long-term regular role in an American show widely available in Great Britain, he raised her prominence to the point that Andy Pryor would have seen her as a reasonable candidate for the high-profile role of River Song.