you are looking for a viggo mortensen address, you probably already heard
that he is not accepting any fan mail.
So the closest address is
his official site, Perceval Press. However, this site also states
that fan mail is not accepted and to please honor this request.
In metaphorical terms, you
can find his address in his movies, his work, and his art.
Here is the link to Perceval
more on viggo mortensen index
Viggo Mortensen Index