Scrum-halves Charlie Mulchrone (Harlequins) and JB Bruzulier (Nevers) and centres Heath Stevens (London Welsh) and Andy Symons (London Irish) have already found other clubs.
Forwards Darren O'Shea (Munster) and Ben Sowrey (Newcastle) also move on.
And the club has already said that long-serving centre Alex Grove will go.
But another centre, Ravai Fatiaki, will also leave, along with hooker Dan George, prop Joe Rees, flanker Mat Gilbert and lock Dan Sanderson
"I'd like to go on record in thanking all the departing players for their efforts during their time at the club," said Ryan.
Warriors, relegated in Ryan's first season in charge, then promoted back up from the Championship a year ago, will finish the season 10th in the Premiership.
Worcester Warriors have so far have made five new signings for the 2016-17 season, headed by rugby league convert Ben Te'o.
They will also be bringing in another centre, New-Zealand-born Jackson Willison from French side Grenoble.
They have also signed three forwards, South Africa-born Northampton hooker Matt Williams, Bath lock Will Spencer and Bristol flanker Marco Mama.
In addition, South African scrum-half Francois Hougaard has completed a move on a three-year contract, having initially signed on loan.
Worcester Warriors director of rugby Dean Ryan has confirmed that there will be 12 players leaving Sixways at the end of season.