I found another disk with a bunch of characters that could be used for aliens and here they are. If I feel ambitious, I might go through the human figure listings and find all the alien looking characters for them. These are mostly unique standalone figures, but there are a lot of Michael, Victoria, P4 Male & Female morphed characters that can also be in this list.

My visual indexes of Poser content are at http://www.sharecg.com/pf/rgagnon