I was going to say Graham as well.
The only person involved with Arsenal that has been successful as a player and manager,
A league title, FA Cup and a European title as a player.
Then two League titles, an FA Cup, two League Cups and a European title, in eight years, as a manager.
As @Drayton said, he also spent very little money.
The famous game against Liverpool, where we won the League, we had a squad consisting of all English players, apart from O'lLeary, mostly from the youth team and the most expensive player was Alan Smith who cost 800k.
Apart from Wenger, no one else has come anywhere close to achieving what he has for our club, in only a few seasons, with spending hardly any money.