Out of contract players Laird and Mousinho have both turned down improved deals while Henry has been released.
Darren Murphy, Ben May, Peter Winn, Stacy Long, Jennison Myrie-Williams, Phil Edwards and Alan Julian have all left the club as their contracts have expired.
Meanwhile, Joel Byrom and Chris Beardsley's contracts are also up but talks over new deals for the pair are set to continue.
Boro's first season in League One was a successful one but their hopes of a third successive promotion were ended this week with defeat to Sheffield United in the play-off semi-finals.
