#9 Shkodran Mustafi (€41 million)
Perhaps one of the best drawn out transfer of the window, Shkodran Mustafi has been linked with Arsenal for what seems like an eternity now. The German international was first linked with the club when club captain Per Mertesacker picked up an injury but signed with Arsene Wenger's side only a few days before the window closed.
The 24-year-old is a solid tough-tackling defender who can outpace most forwards in the Premier League. Having already played in England before, Mustafi knows the language and is acclimatised with how physical and quick the game is.
The former Valencia and Everton man is the kind of centre back Arsenal have needed for a while and looks like a promising prospect who could set right Arsenal's frailties at the back.