Sol Campbell
One of the more controversial signings of Wenger's tenure, bringing in a player who had spent the previous decade with arch-rivals Tottenham Hotspur.
That Sol Campbell arrived as a free agent made this swoop all the more impressive, proving a rock in the heart of defence for five seasons before joining Portsmouth.
Two Premier League titles - one of those coming in the famous Invincibles campaign - and two FA Cups was certainly a good way to win over those supporters who initially had some doubts about his allegiances.
Campbell would return for a second spell in 2010, which it is fair to say was less successful, but his name is rightly remembered for that glorious era in the early-to-mid noughties.