[quote=Raineh Daze]
Only as an April Fool's joke. I'd take anything from Strange Fake with more than a pinch of salt, unless it's been shown somewhere else. XD Rumours cannot become Servants. The entire mechanism by which a Heroic Spirit exists requires a person in the first place.
[/quote]

I know this doesn't really prove anything due to the fact that the Holy Grail was corrupted at the time, making any manner of weird shit possible, but what about Sasaki Kojirou (Fake Assassin). He was an Imitation Servant or a "Shade" based on a legend about a person who never actually existed.