The Collaborative International Dictionary
Apostolic delegate
Apostolic delegate \Ap`os*tol"ic del"e*gate\ (R. C. Ch.) The diplomatic agent of the pope highest in grade, superior to a nuncio.
WordNet
apostolic delegate
n. (Roman Catholic Church) a representative of the Holy See in a country that has no formal diplomatic relations with it
Usage examples of "apostolic delegate".
Now I don't think he's got much choice: First apostolic delegate to an alien race, or something.