Ānanda

The Buddha's cousin and attendant for twenty-five years, and the tradition's memory: at the First Council he is said to have recited the discourses from recall, which is why nearly every sutta in the Pāli canon opens evaṃ me sutaṃ — "thus have I heard."

The canon exists because one man remembered it out loud. He is also the one who argued the Buddha into ordaining women.