Everyone here is lying, no way the hardest hole you've EVER played is on a course everyone has heard of.
The hardest holes are found on the Painswicks of the world, i.e. the type of courses that no one who lives further than 100 miles away ever hears of, unless they become world famous amongst 1500 or so people worldwide
I could name a couple holes on courses none of you have ever heard of that are harder than any hole anyone has named here....or at least any hole anyone has named that I've played or have seen on TV and am willing to render the kind of sight-unseen judgement that drives Patrick Mucci to post in
green One's a lengthy par 5 of I think 570 yards with a double dogleg where the fairway slopes in the opposite direction of both doglegs. It requires a precise drive working the ball perfectly to stay in the fairway and have a shot where playing one's third from less than 200 yards is a reasonable goal. Then you just have to do it again, this time working the ball the other way from a lie completely ill suited to the task, leaving a third from a steeply downhill lie unless you thread the needle inside the last 80 or 90 yards to the green. If you are insane and want to hit a 250-300 yard shot at the green from a crazy lie, there are trees and water on both sides of the last 100 yards through the green. No real gimmicks, it just requires such perfection that even scratch players feel amazingly fortunate to come away with par. The tour could play there and unless conditions were absolutely perfect for scoring I'd bet heavily on the average exceeding 5 shots on that hole. But don't worry, the next hole is a 320 yard par 4 with little trouble which helps take the sting out of a bogey 6!
The other is a 180 yard par 3 with a small green on top of a cone shaped hill where the ball rolls about 60 yards away (and 50 feet down) the closely cropped hill in any direction if you miss the green. Usually backs up 3 groups on the tee while you watch the groups ahead pitch it up and have it roll back down, repeatedly. Total gimmick hole, but I can't think of a hole I've ever seen that had a worse scoring average for average golfers where no one ever took a penalty stroke!