Defenders Aidy White and Lewin Nyatanga are among 10 Barnsley players who are set to be released by the South Yorkshire club.
Left-back White and centre-half Nyatanga will not be offered new deals, while Callum Evans, Ryan Williams, Matty Templeton, James Carvell, Jake Charles, Jack Cowgill, Omari Patrick and George Proctor will also become free agents this summer.
“The club would like to thank all of these players for their services to the club and we wish them all the very best of luck in their future careers,” Barnsley said on their official website.
Midfielder Josh Scowen and striker Marley Watkins have both been in talks with the club about new deals but have “expressed an interest to explore other options”, the club confirmed.
Under-23s captain Jared Bird has been offered a new deal, while loan players Gethin Jones, Matty James, Callum Elder, Adam Armstrong, Ryan Kent, Saidy Janko and Julio Rodriguez have returned to their parent clubs.