Board Thread:Questions and Answers/@comment-1038387-20120921185155/@comment-1038387-20130413065651

Cal-K-Leb wrote: How many people know Dick Grayson is Nightwing? Who are the people who know he is Nightwing and when did they discover his secret

In season one, Bruce, Alfred, Wally and Ra's (and probably Talia as well). In season two, Tim, Kaldur, M'gann, Conner, Artemis, Zatanna, Barbara, probably Rocket. We don't know when and how they found out.