Aach
From Wookieepedia, the Star Wars wiki.
Aach was the code name of the Rebel agent who informed Garm Bel Iblis in 0 BBY of the Death Star plans. Directly answerable to Bail Organa, Aach was a special messenger that was only used for top-level Alliance business.
Though he was willing to forgo his return to Alderaan and accompany Bel Iblis on his mission to Darkknell, the senator sent him back to Organa, firm in the belief that Aach would be needed elsewhere.
