What is Voldemort's Boggart?

Question

Inspired by this question about Hermione Granger's boggart.

What would Voldemort see for a Boggart?

I know it is not in the books, but maybe it is revealed somewhere on Pottermore/interviews?

Answer 1

His own corpse

This is what JKR said:

ES: MuggleNet “Ask Jo” contest winner Asrial, who’s 22, asks, “If Voldemort saw a boggart, what would it be?”

JKR: Voldemort's fear is death, ignominious death. I mean, he regards death itself as ignominious. He thinks that it's a shameful human weakness, as you know. His worst fear is death, but how would a boggart show that? I'm not too sure. I did think about that because I knew you were going to ask me that.

ES: A corpse?

JKR: That was my conclusion, that he would see himself dead.
_{-accio quote}

Answer 2

One additional idea here would be a representation of the unknown. (Not entirely sure what that would look like) Evidence for this would be the two times that Voldemort has prolonged duels in the books his times of doubt appear to be when it is possible that there is something he does not know.

During Order of the Phoenix when Voldemort duels Dumbledore he is surprised that Dumbledore "does not seek to kill [him]" to which Dumbledore replies "there are much worse things than death" This appears to incense and inspire greater fear in Voldemort.

You do not seek to kill me, Dumbledore?” called Voldemort, his scarlet eyes narrowed. “Above such brutality, are you?”
“We both know that there are other ways of destroying a man, Tom,” Dumbledore said calmly. “Merely taking your life would not satisfy me, I admit —”
“There is nothing worse than death, Dumbledore!” snarled Voldemort.
“You are quite wrong,” said Dumbledore, speaking as lightly as though they were discussing the matter over drinks.
“Indeed, your failure to understand that there are things much worse than death has always been your greatest weakness...
_{Harry Potter and the Order of the Phoenix}

The second case of this is in the final duel with Harry when Harry points out that he "knows things that you don't, Tom Riddle" to which Riddle reacts with "a flicker of doubt".

Without getting too deep, a fear of death is often interpreted as a fear of the unknown. It is possible that simply a shadowy figure moving threateningly towards Tom Riddle, one that he cannot easily defeat, would strike the greatest fear in him.