His vast achievements at Old Trafford have set him apart as perhaps the greatest manager ever to have graced the game.
In saying this, who would be the manager currently working who most closely resembles Fergie, both in success and personality?
Or how about Shakhtar Donetsk boss Mircea Lucescu? Here's a breakdown on how the Romanian compares to Sir Alex.
Sir Alex Ferguson was first appointed manager of Scottish side East Stirlingshire in 1974 at the incredibly young age of 32.
Mircea Lucescu was 34 when he started his management career at local side Corvinul Hunedoara, and like Fergie, he had a brief spell in charge of his national team, Romania.
Unlike Sir Alex, though, Lucescu toiled throughout the 1990s, bouncing from club to club, most notably spending an unsuccessful season in charge of Inter Milan.
But it has been his long and fruitful nine-year spell at Shakhtar Donetsk that earns him the comparison.
We all know about Sir Alex's successes at Old Trafford, but for those who need reminding, here's the rundown:
He's won three Scottish Premier Division titles, four Scottish cups, 12 Premier League titles, five FA Cups and two Champions League titles.
Lucescu may not have had the same level of success over the course of his career, but his list of honours is still impressive.
The Romanian boss has won six Ukrainian League titles, two Romanian League titles, two Turkish Super League titles and a UEFA Cup.
He has transformed Shakhtar from pretenders to the dominant side in Ukraine; the Manchester United of the country, if you will.
Perhaps the defining reason for both Sir Alex Ferguson's success and longevity at the top, has been his ability to adapt to the ever-changing nature of the game.
He has overseen countless players come and go at Old Trafford while adapting his team's tactics multiple times.
The same can be said of Lucescu. He spent two years apiece at Besiktas and Galatasaray and won the league at both.
His Dinamo Bucuresti team of the late 80s was typically adventurous going forward, playing the kind of quick attacking football he is now known for at Shakhtar.
He has successfully integrated a key Brazilian core into his current team, mixing players like the tricky Alex Teixeira and Luiz Adriano with the more traditional Darijo Srna and Oleksandr Kucher.
Sir Alex is one of the best at man management in the current game.
He does not pretend to be his players' friend off the field, but does genuinely care for those he coaches.
According to club stalwart Paddy Crerand, "I'm sure the players will be just as pleased and the younger generation of players look up to Sir Alex as a father figure" (via Daily Mail).
Mircea Lucescu too, a man who can speak five different languages, can be described in such a way.
He is a supreme authority with enough experience to know when to be cruel, and when to be kind.
When Luiz Adriano scored a highly controversial goal in a recent Champions League clash, Lucescu wasn't afraid to criticise the behaviour of several of his players.
"I would like to apologise for the goal scored by us, which caused much talk. We wanted to let the opponents score, but [Taras] Stepanenko prevented us from doing so," he said (via The Guardian).
When both Ferguson and Lucescu eventually decide to call time on their illustrious careers, what will be the defining legacy they leave behind?
In Sir Alex's case, there will always be the detractors who grasp at straws for possible criticism, but his record speaks for itself.
He was a great, if unspectacular player who found his true calling as a coach and as an inspirational leader of men.
Lucescu was also a talented footballer in his younger days. As a manager, he's implemented aspects of the attractive style of football he'd learnt to play as a diminutive, pacy winger.
Both will eventually be defined by their time at only one club—Fergie at United; Lucescu at Shakhtar.
Health problems have led to doubts that they can continue coaching for much longer, but as long as there is breath in their bodies and their passion for the game remains, it is difficult to envision a world without either pacing the sidelines.
Who else in management today could you compare with Sir Alex?