Batsman Gordon Muchall and veteran Gareth Breese have signed extensions at Durham until the end of the 2015 and 2014 seasons respectively.
Muchall, 30, was only used in short-form cricket during 2013, contributing 516 runs in 23 games.
Former West Indies spinner Breese, 37, made 19 appearances in all competitions with 18 wickets and 325 runs.
Australian seamer Callum Thorp has not been offered a new deal and ends a nine-year association with the county.
Thorp, 38, was a key part of the Durham side that won the County Championship in 2008 when he took 58 wickets and followed that with 30 in 2009.
He follows Will Smith, Ruel Brathwaite and Mitch Claydon out of the club, with Steve Harmison also tipped to end his career.