Can a person listed on the board of directors of a corp be considered a principal ?

In what context?  Certainly, a high level employee or director might be referred to as a "principal" of a corporation, but that would not make him/her an owner.  I'm not sure what your real question is, though, since, even if someone was a corporate shareholder (i.e. an owner), he/she would not, as a general rule, have any liability for corporate obligations.