We know that some people were aware of the fact that Lord Voldemort was Tom Marvolo Riddle prior to his return in Goblet of Fire; at the very least his close soon-to-be-Death-Eater "friends" and Albus Dumbledore:
“Very few people know that Lord Voldemort was once called Tom Riddle. I taught him myself, fifty years ago, at Hogwarts..."
... underwent so many dangerous, magical transformations, that when he resurfaced as Lord Voldemort, he was barely recognizable. Hardly anyone connected Lord Voldemort with the clever, handsome boy who was once Head Boy here.” (Professor Dumbledore to Weasleys, Chamber of Secrets, CHAPTER EIGHTEEN, Dobby’s Reward)
“Voldemort,” said Riddle softly, “is my past, present, and future, Harry Potter…”
He pulled Harry’s wand from his pocket and began to trace it through the air, writing three shimmering words:
TOM MARVOLO RIDDLE
Then he waved the wand once, and the letters of his name rearranged themselves:
I AM LORD VOLDEMORT
“You see?” he whispered. “It was a name I was already using at Hogwarts, to my most intimate friends only, of course. ... (Tom's Diary manifestation in the Chamber of Secrets).
Who - based on canon (books/interviews/pottermore) - knew about the fact that Lord Voldemort was Tom Marvolo Riddle prior to Ginny being taken to the Chamber of Secrets?
Obviously, Albus Dumbledore and Tom himself. Who else?