Except for all the French, and neighbouring French-speaking countries... (and probably other European countries, but I wasn't exposed to their education system).
Pepin of Heristal was the most powerful man of Austrasia, from one of the most powerful families in the Frankish world (descended from Rhenan Frankish royalty). His ancestry includes extremely prestigious bishops and lords.
There's nothing about him that screams "nobody".
Of course not everyone knows what he did. Most people aren't all that interested in history. You could say the same thing about most historical figures. As a quick guess Julius Caesar, Napoleon and Hitler are the most obvious of a pretty short list of counterexamples that are so well-known that almost everybody has at least some idea of what they did. Even that is going to be pretty limited: I suppose a lot of people here in Belgium are aware of Caesar because he came here to conquer, and provides the oldest written sources of our regions. But not a lot of people are aware of his role in the end of the Roman Republic.
It’s a shame that outside of historical circles and the well read nobody knows who Charlemagne is, or they know he was a person but have no idea what he did. To me the “Dark Ages” are just as, if not more, fascinating that the Imperial era of Rome. I also do think that (Dark Ages) is a good term if applied a little earlier to right after the fall of Rome until the rise of Charlemagne.