1. Andriy Shevchenko
Bought for: £30.8m by Chelsea in 2006
Sold for: Free to Dynamo Kiev in 2009
Chelsea's decision to pay a club-record £30.8m fee for AC Milan striker Sheva in 2006, also breaking the British transfer record for a 29-year-old arguably well beyond the peak of his powers.
Shevchenko's arrival at Stamford Bridge proved controversial and ultimately proved to be the most costly mistake in Premier League history from a profit-and-loss standpoint, with the £30m investment yielding just 22 goals and nothing in terms of a sell-on fee when shipped off to Dynamo Kiev three years later.