Found a few to add:
Najja the Parched - Memphis - Gate of the Palm - Desert Waste outdoors
Sudi the Groveler - Nile Floodplain - Cave just before Sais. After appearing once,
was replaced during 3 subsequent farming runs by Akiiki the Black. Reappeared
after progressing almost to the end of Act II, but again was replaced by Akiiki
after a single appearance.
Dark Spirit Conduit - Memphis Outskirts - Tomb - This thing explodes in some kind of Nova when it dies, so caution.
Mind Raker - Thebes Outskirts - Mysterious Tomb
I also encountered a Harpy-type hero I don't think is in the list yet, but I didn't get a screen. It was named Rahema Gapemaw, and appeared on the path leading to the cave just before Sais.