Among those leaving Franklin's Gardens are forwards Samu Manoa and Salesi Ma'afu to reigning European champions Toulon, together with Phil Dowson (Worcester), Alex Day (Cornish Pirates), Joel Hodgson, Tom Ryder (both Yorkshire Carnegie), Will Hooley (Exeter) and Dom Waldouck (London Irish).
"We are saying goodbye to a number of players this summer," Saints rugby director Jim Mallinder said.
"For a squad to be successful it needs all of the players to have a positive attitude throughout the week, not just on match days, and to contribute in training and in meetings, as well as in the games.
"The players who are leaving have all played their part in helping establish us as one of the top teams in England over the past few years, and we wish them well for their future."
Among Saints' previously announced summer arrivals, meanwhile, will be England and Newcastle prop Kieran Brookes, Sale Sharks forward Michael Paterson and Munster fly-half JJ Hanrahan.