With the story of Bart Bass' brother coming to Gossip Girl (possibly as a result of Bart's untimely demise?), Entertainment Weekly reports that the show has cast Desmond Harrington to play Jack Bass for a multi-episode arc.
He currently stars on the Showtime series Dexter.
On Gossip Girl, Jack Bass first appears in New York City in early 2009 to see the Bass clan through a crisis. Fan theories abound on what that could mean.
As for Quinn, Desmond Harrington's character on Dexter, the Showtime hit is done shooting for this season. So this doesn't mean he's leaving that show.