We're talking head circumference/ volume, not ego here.
What helmets do climbers with a larger head favour?
For context I've had a Grivel Salamander for ages which fits great - plenty of space even with a hat on underneath.
But I've just ordered a Petzl Meteor, size M/L, and it feels right on the borderline of fitting - with a beanie the adjuster at the back has to be fully open.
The Salamander fits up to 62cm and the Meteor 61cm supposedly.
Cheers