But could any of them prove of interest to current manager Phil Parkinson, who is set to lead an overhaul of his squad this summer?
Scroll down and click through the pages to see the former Black Cats available as free agents this summer – and let us know whether there are any you would take back:
5. Adam Matthews
The Welsh international signed a one-year deal at Charlton last summer after being released by the Black Cats, and could be on the move once more. He'll also stay at the Valley until the end of the 2019/20 season after signing a temporary extension. Photo: Alex Davidson
6. Steven Fletcher
The Scottish international has netted 13 times already this term and, while Sheffield Wednesday were keen to extend his stay in South Yorkshire, he’s turned down a new deal. Photo: Mike Hewitt
7. Jack Colback
Having fallen well down the pecking order at Newcastle United, Colback hasn’t played competitive football in almost a year and is now set for a summer switch. Photo: Alex Livesey
8. Daryl Murphy
Recently released by Bolton, Murphy netted eight times last term in a struggling side. Could he be worth a punt? Photo: Alex Livesey