Kill me, then! You will not win, you cannot win! The wand will never, ever be yours–
Who: Gellert Grindelwald
Source: Source: Harry Potter and the Deathly Hallows by J. K. Rowling
Note: Voldemort has tracked down Grindelwald at Nurmengard, the prison he himself had built for his enemies, believing he can lead him to the Elder Wand. At that moment, Bellatrix Lestrange summons him to the Malfoy Manor because they have Harry, and he kills Grindelwald in exasperation.