The former Manchester United assistant spent five years at the Riverside – a spell which saw Boro win the 2004 Carling Cup trophy and reach the 2006 UEFA Cup final. The Teessiders also made some terrific signings under McClaren - scroll down and flick through our gallery to see the best of them:
5. (7th) Gaizka Mendieta
Two years after signing for Lazio for a whopping sum of around £43million, Mendiata ended up at the Riverside - initially on loan. No fee was involved as the Spanish midfielder joined Boro permanently in 2004, after helping the club win the Carling Cup in February that year. Photo: Stu Forster
6. (6th) Bolo Zenden
His penalty at the Millennium Stadium may not have been the most convincing, but the Dutch international did open the scoring during Boro’s Carling Cup triumph. Zenden only spent two years at the Riverside and joined the club on a free transfer in 2004 after a loan spell on Teesside. The midfielder was voted fans' 2004/05 Player of the Year before moving to Liverpool at the end of the campaign. Photo: Ross Kinnaird
7. (5th) Mark Viduka
A lethal finisher, the Aussie striker netted an impressive 41 goals in 98 appearances during his three years at Boro after arriving from Leeds United. Among them were some memorable strikes in those UEFA Cup comebacks against Basel and Steaua. Photo: Mark Thompson
8. (4th) George Boateng
Snapped up for around £6million from Aston Villa in 2002, the holding midfielder became an instant regular at the Riverside. Boateng played a part in the club's Carling Cup and UEFA Cup success and was handed the captain's armband once Gareth Southgate switched from player to manager. Photo: Alex Livesey