Enniakosioenenekontenneaphobia

Enniakosioenenekontenneaphobia (from Greek enniakosioi, "nine hundred", enenekonta, "ninety", and ennea, "nine") is the fear of the number 999. The most common trigger is that 999 is 666 upside-down. 666 is the Number of the Beast, a reason why the number is commonly feared. This number is not as commonly feared as enneaphobia, fear of 9, and enenekontenneaphobia, fear of 99. Unlike those two other fears, the reason from being one away from the higher-digit number is not a common contributor for fear of 999.