Sir Alex Ferguson

Sir Alex Ferguson managed Manchester United for 26 years (1986–2013), winning 38 trophies including 13 Premier League titles, 5 FA Cups, and 2 Champions League titles. His ability to rebuild squads across different eras — the Class of '92, the Cantona era, the Ronaldo era — is unmatched in management history. He never finished lower than third in the Premier League in his 21 full seasons there. He was knighted in 1999 following the Treble. No manager in the history of any major European league has held one position of such success for so long.