Although probably not rare due to the age he lived to is T. O. M. Sopwith.
However, I like the example of his autograph that is on public display which not many people know about due to its location.
The fin of the Sopwith Pup displayed at the Museum of Army Flying has his autograph on it but due to the aircraft's positioning in the museum the public view the portside of the fin and don't see the autograph.