Definitely right, Nicky. Lance Reddick is another one (also starred in Lost with Kirk Acabvedo and Ken Leung, the last of whom was also in Soprano's) Method Man (Tug Daniels in Oz, Cheese Wagstaff in The Wire) and Seth Gilliam (Ellis Carver in The Wire and the screw turned inmate Clayton Hughes in Oz) Almost certain there'd be more, stuffed if I can think of any others right now but.

Actually, there are a bunch of solid character actors in it who can be seen in heaps of different series.

But Oz, as the first hour length HBO drama, definitely led the way. I personally feel that The Wire, Soprano's, Deadwood and even non HBO productions such as Brotherhood and Breaking Bad owe a huge debt to Oz as a reference point for pushing the envelope in regards to crime-drama.