I vote for either of these:

Medieval Faire;
Polit (Government);
Intelligence Agency (Spies).

The Bureau-goverment/secret police (you could make a case for being against most any clan)
bonus--copy bonus?--+1 pill--

Necro strikes again

@Minion4D

I think it's a little hard to pin to pin down cards as good or evil- as their backstory basically requires a reason they'd be fighting every other clan out there, no cards are strictly good or bad. I mean, you could argue Fang Pi Clang and Pussycats are both evil, as one is seeking world domination from a Bruce lee clone and the other is supposed to be outright sexist (some characters are portrayed as merely feminist, but according to the clan description they view men with outright disdain). Oh, and I would count Nightmare among the classical 'evil' clans before I'd put in Piranas, and Freaks are usually thrown in there too.

But including the six you listed and the other two usually a categorized as 'evil', that puts them at eight, and most the other clans are in the grey area rather than on the light side. That aside, the underground reptilians idea would be fun to see, and I may have mentioned something to that effect earlier.

Mythical Creatures

Correction. The first two times I said cards, I meant clans.

@DarthTx I noticed someone had mentioned about Eloxia, i thought it was a good idea for a clan so I put my vote behind it.
I just like following how the comics portrayed the clans.

Robots?

How about a clan full of drunken people? Perhaps a drunken russian clan xD

Well these also sound nice:
- Political Clan
- Gamer Clan
- Dwarf Clan
- Ninja Clan with no artwork at all, since you can't see ninjas
- Medieval Clan
- Dinosaur Clan
- Superhero Clan

Anyway, I'm for the drunken russians clan.

Selios, a fusion between the Helios (Sun) and Selenes (Moon).
The nobleman and the noblewoman who live for the virtue and the peace.
The Chaos Lords (live under earth) who hate the humains and want to destroy all of their path.
And more clans like that...