I don't think I've ever heard that fastener called an Allen bolt, just the tool (Allen key). I've generally heard them called hex sockets heads. Maybe it's a regional thing?
In Dutch they are called "inbus", which apparently comes from the German name "Innensechskantschraube Bauer und Schaurte", where Innensechskantschraube means inside six sided screw and Bauer und Schaurte is the company who patented the screw type.
That's not true when working internationally, since it can have different names in different nations. In Italy is Brugola, in Germany Inbus and in other places it has other names. Everyone understands what a hex key is though