Great list. I do agree that the Wraith have almost become an after thought - wonder why?

I would have added the BORG from Star Trek - that hive mentallity and the overwhelming numbers. Similar to the replicators, but add to it some people you know who've been converted and it ups the ante. But like you said when they become unbeatable or too familiar they lose some of their menace.

No #8 *hee* - someone is protecting thieir villinous identity.