Question: Who thought atoms and the void comprised all of reality?
Disambiguated questions and answers: question: Who originally thought atoms and the void comprised all of reality?
Who, as a student of Democritus, thought atoms and the void comprised all of reality?
answer: Democritus
Epicurus
question: Who is the mentor thought atoms and the void comprised all of reality?
Who is the pupil thought atoms and the void comprised all of reality?
answer: Leucippus
Democritus
Natural Questions answer: Parmenides of Elea (from the Wikipedia article "Parmenides")