Dein helped to bring Wenger to north London in 1996 and, almost two decades later, Arsenal have firmly established themselves as one of the most envied clubs in the world.
Wenger is the man who can take most responsibility for that according to Dein, who thinks he will be an "impossible act" to follow when he finally leaves the club.
"He has transformed the club, revolutionised the club," Dein said in an interview on Sky Sports 1
"Whenever he decides to leave he will be leaving behind a phenomenal state-of-the-art training facility, a wonderful stadium, a very good squad which he is trying to improve and a legacy of what he's won
"Arsene is a football purist
He has a lovely phrase, he calls it 'possession with progression'
"Arsene Wenger transformed the club on the pitch and off the pitch
I will go on record as saying he won't be a difficult act to follow, in my opinion it will be an impossible act."
Wenger will reach the 1,000-game landmark against Chelsea at the weekend and - following Sir Alex Ferguson's exit from Manchester United last summer - Dein does not expect another manger to come close to matching his record.
"I would go on record and say I don't think we will see that again in our lifetime," he said.
"It's a phenomenal milestone; 1,000 games at one club for 18 years
In modern football the longevity in the whole of the 92 professional clubs, you know how long a manager stays in his job for? Eleven months, and Arsene has been there for 1,000 games which is absolutely astonishing."
Despite not winning a trophy for eight years Dein believes Wenger's record at Arsenal stands the test of time.
"He's won three Premier League titles and two doubles in that of course," he said
"Four FA Cups, he is the longest-serving manager in the Premier League today and he has, if I'm not mistaken been manager of the month 13 times which is in itself more than anyone else other than Sir Alex Ferguson, so he leaves behind a phenomenal legacy of what he has achieved on the pitch but also off the pitch.
Wenger is yet to agree a new contract - his current deal expires in the summer - to create some uncertainty over his future
Dein is certain, however, that he has the passion to stay on, adding: "He still has the fire in his belly and wants to win every game
"We have a ritual that after a home game we go up the road and we normally have dinner together with his wife and my wife - but only if we haven't lost
If we've lost he's bad company
It's a monologue instead of a dialogue.
"The other day I said to him you've probably had 1,000 games with other clubs and 1,000 with Arsenal, you've probably had collectively about 2,000 games
"I asked what does that mean to you? He looked at me and said: 'Two thousand sleepless nights'
"That tells you a lot about the man."
Source : PA