Best known as the surprisingly historically existent inspiration for Afro Samurai and and loyal samurai of one Oda Nobunaga. If befriending the borderline literal Demon Lord of feudal Japan doesnt get you weeb cred, literally nothing will. ^_~
If his biography starts to read like the history of subbed anime and birth of the computer RPG, theres a a reason for that. It is actually entirely possible that JRPGs and accessible anime as we know it today wouldnt have existed without him laying the foundation, hence why I respectfully like to refer to him as Weeb Prime.
Hmmm, the above article above has a lot less about him than I recall... Seems I still wasnt able find a detailed history, but this account of how some of the very first subbed anime came to be under AnimeEigo with Robert Woodhead and Roe Adams might shed some light on what I mean. ^_~
Francis Xavier (Saint Xavier) maybe. He was the first Christian missionary to Japan in 1549 and adopted alot of their culture to help spread Catholicism and Christianity. There were European merchants before him though so there most likely a weeb in that mix.