But could any of them prove of interest to current manager Phil Parkinson, who is still eyeing some new additions before the second transfer deadline on Friday, October 16?
Scroll down and click through the pages to see the former Black Cats still available as free agents this summer – and let us know whether there are any you would take back:
1. Danny Simpson
After spending much of last summer in the wilderness, Simpson penned a deal at Huddersfield Town the season - but he left the Terriers this summer and is yet to find a new club. Photo: David Rogers
2. Jordan Cook
A Sunderland academy graduate, Cook was released by Grimsby Town in the summer and is yet to find a new club. With bags of EFL experience under his belt, he could prove a good pick-up for someone before the window closes. Photo: Pete Norton
3. Will Buckley
Recently on the books of Bolton Wanderers, Buckley is still looking for a new club as he looks to revive a career which had shown great promise. Photo: Nathan Stirk
4. Joel Lynch
Released by Sunderland in the summer having struggled for regular game time under Phil Parkinson, Lynch is still without a club - despite spending part of the summer training with League One rivals Charlton Athletic. Photo: George Wood