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:
5. Lee Camp
We’re pretty sure nobody will want him back at Sunderland. But nonetheless, his contract at Birmingham City was up at the end of the 2019/20 season and he remains without a club. Camp was linked with Salford earlier this summer, but a deal failed to materialise. Photo: Lynne Cameron
6. Adam Matthews
The full-back has spent much of the summer training with former club Charlton Athletic after his deal at the Valley expired at the end of the 2019/20 season. He's yet to agree to fresh terms though, so remains a free agent. Photo: David Rogers
7. Callum McManaman
Another who has spent time training with a former club in Wigan, McManaman has been linked with a host of clubs but is yet to put pen to paper anywhere. Photo: Jack Thomas
8. Duncan Watmore
While he was linked with Championship side Reading earlier this summer, Watmore is yet to find a new home after his long spell at Sunderland came to an end. Photo: Jordan Mansfield