A phenomenon where a historical (or otherwise original) figure gets overshadowed by its version from modern culture. Named after Astolfo, who is originally a character from a French legend, but most
people nowadays know him from the Fate anime franchise as the
guy who looks like a girl, also referred to as
trap or femboy.
Most prominent if you try to look their images up. There are even more famous examples, such as the infamous dictator Nero Claudius.
A: I tried to search for some pictures of this
guy for my school
presentation but all I could find was this anime girl for some
reason.
B: Yeah, that's the Astolfo effect for you.