Something that always bothers me when I read any kind of fantasy or historical fiction is seeing people or families associated to lions, which if I'm not terribly mistaken, are only native to Africa.
Now, I understand that just because an animal wasn't native to Europe it doesn't mean medieval populations weren't aware of it, but the iconic recognition the image of the Lion has is something that, as far as I know, usually only happens no native things with which the population deeply identifies (the kind of animals that become associated with certain people, families, and subsequently nations), so that presents a potential problem or cognitive dissonance in my mind.
The lion is not only native to Africa. Even today there is a wild lion population in the Gir Forest, Western India. And I say "even today", because up the the early 20th century lions also lived in North Africa and the Middle East. The last one in Morocco was killed in 1922 and the last one in Iran was seen around 1940. In the Middle Ages, lions were also present in Anatolia and the Caucasus, and in Ancient times they inhabited what is now Greece and Bulgaria. Excluding the Pleistocene cave lion, that lived in most of Europe and northern Asia during the Ice Ages, the top limit of the modern lion's distribution in Europe was modern Hungary, where lions were present in the Neolithic (see Bartosiewicz (2009), A lion's share of attention).
So, were Medieval Europeans familiar with lions? Verily. Lions have always been a favorite animal of people. They appear constantly in art, heraldry and literature. Anyone with a passing knowledge of Rome would be aware of the lions used in circus games and victory triumphs. And if they weren't, lions are mentioned in the Bible several times.
Were there free lions, in the wild, in Europe, during the Middle Ages? No, unless you count the Caucasus as Europe, as I mentioned. The lion was driven to extinction in the Balkans around the time of the Roman conquest. There were lions in North Africa, Anatolia and the Holy Land when Crusaders went there, though.
Were there lions alive in Europe during the Middle Ages? Yes, in captivity, kept in private zoos (menageries). They were prestige items and often exchanged as diplomatic gifts between monarchs and lesser nobles. The kings of England kept lions in the Tower of London since the 13th century.
hi! in-depth answers are welcome here, but meanwhile, here's a recent post; it includes a link to a related FAQ section too