[51Cards]

If we really want to get particular there was OV-098, Pathfinder, though being made of wood it obviously was never meant for more than fitment testing. Oddly though it did get the OV designation, not the STA designation.

[mystified5016]

Huh, I wouldn't have thought that what is essentially a mock-up would merit a designator or a name.

[Dalewyn]

Mockups that were particularly detailed and well-preserved (OV-098 Pathfinder) or appreciated (OV-095 SAIL) were given honorary Orbiter Vehicle designations.

Further reading: https://en.wikipedia.org/wiki/Space_Shuttle_orbiter#Orbiter_...