Next up, Maximilian Sforza, son of Ludovico Sforza, aka Ludovico il Moro. Maximilian was Duke of Milan and ruled from 1512 to 1515. He looks very ginger in this picture!
Following on from Maximilian we have another Italian, Isabella of Aragon, Duchess of Milan. She was also known as Isabella of Naples. Some have suggested she was the sitter for Leonardo da Vinci's famous Mona Lisa painting. In this portrait by Giulio Romano, a pupil of Raphael, she looks very Mona Lisa-like. Complete with thick reddish hair.
Next we mover to more northerly climes. I found these two pictures whilst looking on-line today. In both the images the people depicted look very red-haired, although I could find no contemporary descriptions confirming this. The first one is John of Denmark, eldest child of Christian II of Denmark. The second is Christina of Saxony, who was Queen consort of Denmark, Norway and Sweden (she married a different John of Denmark).
Actually, I've just been looking into things further and it turns out that John of Denmark's mother was also red-haired (at least according to her pictures). She was called Isabella of Austria - yet another red-haired Isabella!
[Update: I've just found out that the picture of Christina of Saxony, shown above, is actually from a Lucas Cranach the Elder work titled Saints Genevieve and Apollonia. So I'm guessing that isn't her ...that'll teach me to go stealing pictures from Wikipedia :p
Still, the two women pictured look fairly red-haired.]