#5 Ashley Cole
Perhaps appropriately dubbed “cashley”, it was again a case of money being at the heart of this transfer. At the turn of the century, Arsene Wenger had entrusted faith in a young English left-back who would go on to be a key component of the side through their unbeaten 2003/04 season.
Two years later though and when a contract offering just (yeah just) £55,000 per week was put on the table, Cole was left fuming and quickly snapped up a £90,000 per week contract with Chelsea.
Cole went on to achieve great things with the Blues, including the UEFA Champions League in 2012, whilst Arsenal had to endure countless trophyless seasons which may have only fanned the flames of hatred felt by fans of the Gunners towards the former-England international.