My five-year-old kid likes stories, and I like history, so I will sometimes tell him about interesting periods in history.
However, just the plain facts are not always that interesting to a five-year-old, so I'd like to talk more about historical characters - not necessarily those that have the most interesting story, but rather those that are good illustrations for important themes & concepts.
For example:
Richard Lionheart's story is a good opportunity to talk about the crusades, the English royal line, the practice of holding nobles for Ransom money, and how much John Lackland sucked.
William the Conqueror is an opportunity to talk about Vikings, the English Crown, Vassal-Liege relationships, and military technology (the use of cavalry, prefiguring the importance of knights)
Any other good ones like that? I'm mostly focusing on "medieval Europe" broadly conceived (knights and castles and all that, but possibly also the dark ages and late antiquity).
Heloise! First she was a super educated brilliant young woman, then she was very in love with Abelard, then she was an important abbess. It's a good way to talk about the church, the kinds of roles educated women could play in monastic life, family jealousy, all kinds of good stuff.
Also Charlemagne. The Carolingian empire is super important and under-studied, and we have a ton of information about him because Einhard wrote a whole biography of Charlemagne.