6: William Prunier
Balding French centre back who arrived in the north west at the start of the 1995-96 season after buying out his contract with Ligue 1 outfit Bordeaux, with Fergie wanting to utilise a continental-style defender in his back four at that time.
However, after a seemingly impressive first-team debut against Queens Park Rangers, the Frenchman then turned in one of the worst defensive displays ever seen in a Red Devils shirt in a 4-1 thrashing at Tottenham Hotspur and he never played another game for the club.
5: Massimo Taibi
Probably the worst goalkeeper the club has ever had, with the flapping Italian lured from Venezia in the summer of 1999 for £4.5m after Denmark international Peter Schmeichel had decided to call it quits at the end of the previous season.
However, after a series of high-profile and costly errors, including one never-to-be forgotten howler against Southampton at Old Trafford, the goalkeeper was soon on his way back to Italy the following summer.