Gary McAllister
Few Liverpool players have made as big a mark on the club during such a brief spell, but Gary McAllister proved to be a shrewd acquisition by Gerard Houllier in 2000 - indeed, the Liverpool boss himself described the Scot as his most inspirational signing.
Then 35 years old, there were certainly eyebrows raised by the decision to bring the former Leeds United and Coventry City man to Anfield on a Bosman transfer, but by the time he left two years later he had made an indelible impression on the team.
McAllister helped Liverpool to the League Cup, FA Cup and UEFA Cup treble in 2001, scoring one and having a hand in three more of Liverpool's five goals in the latter as he scooped the man of the match award from their action-packed 5-4 victory over Alaves.
McAllister's most memorable Liverpool moment came at Goodison Park, though, where he scored a 44-yard free kick in the fourth minute of stoppage time to hand the Reds a last-gasp victory over Merseyside rivals Everton during his first season at the club.
In his two years at Anfield McAllister scored nine goals in 87 appearances, helping the club to five trophies along the way before taking up a player-manager role at Coventry.