But which players are still available this summer who could be interesting the Black Cats? We take a look at the best players still available who could realistically arrive at the Stadium of Light in the coming weeks – scroll down and click through the pages to see who could be available as transfer business ramps up:
9. John Marquis (Doncaster Rovers)
A £1million fee is thought to be enough to prise the prolific striker from Doncaster Rovers - with Sunderland known to be fond admirers. With a striker addition looking necessary, Marquis could be a perfect fit.
Photo: Ross Kinnaird
10. Herbie Kane (Liverpool - loan)
The Liverpool youngster excelled on loan at Doncaster Rovers last season and could be allowed to leave Anfield again. Interest will be high after Kane's stellar performances last season.
Photo: John Powell
11. Jason Cummings (Nottingham Forest - loan)
Tentatively linked with the Black Cats last summer, the Scottish international looks to be available again this summer. Get him firing and he could be a real handful in League One.
Photo: Kate McShane
12. Bobby Duncan (Liverpool - loan)
The young striker has been prolific in the Reds' academy set-up and could now be set for a loan move to further his development. He wouldn't be a proven option, but a calculated gamble may be worthwhile.
Photo: Nick Taylor/Liverpool FC