Someone who mentally scars you every time you see them. Typically, the person being scarred is a faggot who is looking at pictures of these so-called scar masters on Google Images.
Scar masters tend to achieve such a status by grinning constantly (see grin king) and/or by being a complete rapist.
Words such as "supreme", "extraordinaire", or "McGee" can be tagged on the end as an intensifier.
Oh my gotti, I shouldn't have typed "Steve Carell" in the search bar. Every picture of him ruins me. He's a scar master supreme!!!!!