Today, let's look at the first appearance of the second--and most enduring--of the impostors: Paul Sloane!
Like Harvey Apollo, this Two-Face was originally an actor, and I can't help but think that the Apollo story influenced this one. But unlike that out-of-canon ham actor, the in-continuity Sloane was actually more of a method actor who got a little too deep in the role! Of all the in-canon impostors, Sloane is the only one who was genuinely scarred and snapped, rather than playing dress-up to frame Harvey.
In fact, Sloane's Two-Face may have affected Harvey's subsequent appearances more than we suspect! We already saw how Batman dressed up as Sloane dressing up like Harvey, and how Sloane was the first Two-Face who actually seemed to have fun being evil, all the way up to an image that damn well feels iconic:

( The greatest of the impostors, behind the cut! )
Like Harvey Apollo, this Two-Face was originally an actor, and I can't help but think that the Apollo story influenced this one. But unlike that out-of-canon ham actor, the in-continuity Sloane was actually more of a method actor who got a little too deep in the role! Of all the in-canon impostors, Sloane is the only one who was genuinely scarred and snapped, rather than playing dress-up to frame Harvey.
In fact, Sloane's Two-Face may have affected Harvey's subsequent appearances more than we suspect! We already saw how Batman dressed up as Sloane dressing up like Harvey, and how Sloane was the first Two-Face who actually seemed to have fun being evil, all the way up to an image that damn well feels iconic:

( The greatest of the impostors, behind the cut! )