Even though Get to Work does have the aliens, I would get that one anyway. That pack is kind of a must-have because of all the other stuff in it.
Because there's so many packs, it will be easier to tell you which ones DO have occult forms:
Get to Work, aliens.
Vampires
Island Living, mermaids. However, the mermaids barely have ANY impact on the game, you'll occasionally seen one swimming around but otherwise they're completely irrelevant. So if the island setting appeals to you, don't let the mermaids put you off.
Realm of Magic, spellcasters.