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Very few people know that Lord Voldemort was once called Tom Riddle. I taught him myself, fifty years ago, at Hogwarts. He disappeared after leaving the school … travelled far and wide … sank so deeply into the Dark Arts, consorted with the very worst of our kind, underwent so many dangerous, magical transformations, that when he resurfaced as Lord Voldemort, he was barely recognisable. Hardly anyone connected Lord Voldemort with the clever, handsome boy who was once Head Boy here.
Also we know that everyone knows that Voldemort was in Slytherin. At least when Ron mentions this
“Gryffindor,” said Ron. Gloom seemed to be settling on him again. “Mum and Dad were in it, too. I don’t know what they’ll say if I’m not. I don’t suppose Ravenclaw would be too bad, but imagine if they put me in Slytherin.”
“That’s the House Vol-, I mean, You-Know-Who was in?”
“Yeah,” said Ron. He flopped back into his seat, looking depressed.
Then how do very few people know the real identity of the Voldemort as Tom Riddle, surely people would have searched and found out this once he disappeared. Actually everyone should know this considering Voldemort is really famous among wizards.