Mr. Scars is a member of the Collective, who uses his past self, Milo Asher, as a vessel. His defining characteristics are the self0inflicted scars running down his arms, which resemble tally marks. The Observer has referred to him as a pawn, as well as "the burdened" and "theonewhokillsmary". He is represented by the ♖ (white rook) chess piece.
Mr. Scars appeared in Milo's dreams in the past and Milo would tell his mother, Mary Asher, that Mr. Scars was going to kill her. On March 1st, 2012, Noah Maxwell tweeted about a dream he had, in which he saw a man with scars on his arms covering his face and crying whilst sitting in a chair and holding a gun. In 'Mary Asher Phone Call', Mary calls Noah and demands to know who Mr. Scars is, not believing that Noah didn't know his identity. Noah would later have further dreams involving Mr. Scars, which he tweeted about on October 20th of that year.
At some point after his supposed death by drug overdose, Milo's throat was slit. Milo, as Mr. Scars, awakened in an abandoned house some time after this, discovering a letter from the Collective that demanded he kill his mother within 120 hours or be killed himself. After being given a briefcase containing a large sum of money and being confronted by the Slender Man, Milo called Mary to meet him and shot her after revealing his identity. Mary's body was later found in a partially submerged car in Alabama. As Firebrand had foretold, Mr. Scars then delivered a briefcase containing the money, along with Milo's journal and several other items, to Noah's house.