So far as I can make out from the element descriptions at
        http://www.loc.gov/standards/mods/userguide/origininfo.html
and related pages, there seems to be no way to express in MODS who the
copyright holder of a work is -- which seems strange, as you CAN state
the copyright date.

Am I missing something?

(The <publisher> element is not the answer here, as it's not at all
unusual for the copyright to be held by someone other than the
publisher -- the author, for example.)