Manfred Grieg
From Tardis Wiki, the free Doctor Who reference
Manfred Grieg, also known as the Man in the Mirror, had been trapped long before inside The Mortal Mirror and was cursed with a perpetual body of glass. He kept a glass diary, which seemed to explain the past, present and future: everything that happened in Castle Extremis. He revealed himself to the Tenth Doctor and Martha, when he realised that something was going on inside the Mirror. (PROSE: Martha in the Mirror)
