Is there a "Canonical" Commander Shepard?
Solution 1:
In each game, there's an option to use a premade default Shepard. This Shepard is a Soldier, Earthborn Sole Survivor. If male, his name is 'John', if female 'Jane'.
Since this didn't change between games, I think we can assume it's as close to canon as anything (and certainly is in the same vein of the didn't-import-a-save options).
