Bailey's arresting officer in ep10
It was only a very fleeting appearance and he wasn't even credited on his wiki page, but it took me ages to figure out who it was.
I knew I recognised the face and voice from a previous law enforcement type show.
It was Sharif Atkins from White Collar (and I'd also seen him in ER before too)
Seemed strange to have such an established actor in a very small roll which didn't even get a credit.
It's only just been updated on his imdb filmography today too.