Destiny
I always thought it was Judge Gallows.
Perhaps you are right. After checking Wiki, it seems Destiny's first appearance was Weird Mystery Tales 1 (1972). But I seem to recall the hooded figure on Unexpected to have the shackles around his wrist with the book of Destiny, maybe my memory is failing me...
I really don't know for sure but since Gallows was in the Unexpected title, I just assumed it was he.
I found this link which is kind of interesting for all the horror hosts.
DC Horror Hosts