Former players Lee Sharpe and David May insist, however, that the "real" Manchester United manager is completely different.
Between them, Sharpe and May spent 17 seasons in Sir Alex's squad, and they were both in the MUTV studio for this week's Thursday Focus show when a viewer, Dick from Weymouth, rang in asking for examples of the manager's softer side.
To hear what they had to say, watch the video above. And don't forget, Thursday Focus screens every Thursday at 18:30 GMT. For MUTV schedules and subscription details, see manutd.com/mutv.