Who said "Horcruxes are the key to conquering death itself."?

This quote is attributed to Voldemort.

Horcruxes are the key to conquering death itself. - Voldemort

"Horcruxes are the key to conquering death itself."

Voldemort Death

"There is no good and evil, there is only power, and those too weak to seek it."

"I have grown stronger than I was, more terrible, more powerful."

"Fear of a name increases fear of the thing itself."

"Failure and death they are but shadows to me."

"Death doesn't scare me anymore."

"Death and I are old friends."

"Welcome to my world."

"Death is just the beginning."