But it is not only at Filbert Street that O'Neill, and his No 2, John Robertson, are revered. They remain legends at the City Ground, Nottingham, their enduring popularity underlined by their inclusion for a recently named team of Nottingham Forest greats.
The team, drawn up as a result of a poll conducted among thousands of Forest supporters to mark the centenary of football at the City Ground, names Robertson, the former lager-swilling, chip-chomping winger, as the finest of them all, with only three entries failing to nominate him.
But the XI, which draws heavily on the team that won the European Cup twice under Brian Clough and Peter Taylor, also includes a place for O'Neill, who played on the opposite flank to Robertson and always felt in awe of his Scottish colleague. He makes regular self-critical reference to the size of his ego but was genuinely flattered to learn of his continuing popularity.
"I was truly delighted to learn I had been chosen," O'Neill said. "I really didn't deserve to be included considering all the great players who have worn the Forest shirt. I can only think that my brother in Nottingham must have run up a pounds 300 phone bill by ringing in with hundreds of votes for me!"