Fine actor and TV narrator, Stacey Keach, is one such mustache wearer. He was born with a cleft lip and a partial cleft of the hard palate. In his business, it was almost a necessity to camoflage all the scars from operations he underwent.
Leni
Another one who comes to mind in this situation was the past Prime Minister of Spain, Jose Aznar. He wore a moustache, and it was to cover a cleft palate, or a scar from surgery. He was a really good-looking fellow too! But I never would’ve guessed with either of these guys wearing one for that reason!