Centre-back Grant Hall is the only player who has joined the Teessiders ahead of the 2020/21 campaign, while other transfer targets have moved elsewhere.
Scroll down and flick through the pages of our picture gallery to see every player who has been linked with Boro this summer and what has happened to them since:
1. Chris Gunter (Free agent)
A rumour which emerged at the end of last season. The 31-year-old right-back is now a free agent after his contract at Reading expired following an eight-year spell at the club. Photo: Stu Forster
2. Charlie Goode (Signed by Brentford)
A player who was on Boro's radar, with some claiming a deal was close, yet the centre-back signed for Brentford instead. Photo: Pete Norton
3. Alex Bass (Portsmouth)
Boro are said to be in the market for another keeper with reports linking them to 22-year-old Bass. Pompey boss Kenny Jackett said earlier this month that no bids had been made for any of his players. Photo: Getty Images
4. Grant Hall (SIGNED)
Boro's only signing so far this summer after the centre-back decided to leave QPR where he was club captain last season. Photo: MFC