Question: Who is Margaret Of Bourbon (1438–1483)'s maternal grandfather?
Answer: John the Fearless

Agnes of Burgundy (1407 – 1 December 1476), duchess of Bourbon (Bourbonnais) and Auvergne, countess of Clermont, was the daughter of John the Fearless (1371–1419) and Margaret of Bavaria. Her maternal grandparents were Albert I, Duke of Bavaria and Margaret of Brieg. Her paternal grandparents were Philip the Bold and Margaret III, Countess of Flanders