We're having a game coming up here soon where we need to build teams based off either the taking over or complete destruction of Asgard. Besides the following groups or individuals, are there any others you can think of?

SHIELD
Maybe Hydra?
The Worthy
Dark Avengers
Dark Elves (and Malekith of course)
Loki

I haven't read many comics, so I was wondering if there were a few others?

Frost Giants from AVM and the big ones from GSX.

Sentry, Void, And The Duo, Also The Hulk And Loki

Hela, Loki, Amora (the Enchantress), Skurge (Warlord), and the Norn Queen (Karnilla) are all well-established as being on the outs with the throne of Asgard from time to time (if not most of the time), so any or all of them would work well as part of an Asgardian rebel team.
Speaking of Loki, he is responsible for both the Wrecking Crew and Absorbing Man, so him with them along as muscle wouldn't be out of place.

Thanos, maybe.

Surtur, with or without the fire demons.

Galactus (hey, an alien demi-god's gotta eat, right?).

Duhg, marauders, and Kronnan Stone Men from the Dark World set.

The Serpent... If you have the FI grand prize then great, but if not the FI Serpent or Cul Borson could lead a team of the Worthy.

Not knowing the point build makes it impossible to know what teams might be possible.

seems to me the New Mutants and the X-Men have had several trips to Asgard....(New Mutants Special Edition, X-Men Annual #9, etc...)

Tanarus? Has the rock troll been clicked in his normal form?

Dark Avengers, Norman Osborne and H.A.M.M.E.R.

Oh man, HoT Ulik is pretty good other than his defense values.

There may be a couple different 'Attack on Asgard' themes to run:

1) The Mythological, not-of-this-world Asgard, mostly seen in comics.

The main forces involved with this sort of battle would be Surtur and his Fire Demons, Ulik/Tanarus and his Rock Trolls, Malekith and his Dark Elves, The Fenris Wolf, Frost Giants and their leaders. The Fear Itself Serpent and his cronies could be involved here as well.

2) Asgard in Oklahoma

This is the Battle for Asgard that would most clearly involve the Dark Avengers and H.A.M.M.E.R. on one side, and could involve the Avengers on the other. S.H.I.E.L.D. could play either side I suppose because of Dark Reign shenanigans.

3) Asgard... in... SPAAAAAACE

This would be more inspired by the Marvel Movie Universe, although those figures are great for the two above. In the MMU, it is clear that Asgard has had dealings with Elders of the Universe, Kree, Skrulls/Chitauri (w/Thanos), and it looks as if there will be some Guardians of the Galaxy and Nova Corps links too.

There are a few 'villainous' (or 'unaffiliated') Asgardians who have played both sides that can be used on almost any force, IMO: Loki, Enchantress & Executioner, Lorelei, Hela, Splitlip and his Dwarves.

The X-families took their lumps in Asgard in the 1980s: Storm was mind-controlled by Loki, Alpha Flight had to deal with mortals getting powers from Asgard, The New Mutants endured some troubles (including Mirage, who became a Valkyrie and Magma who became an Elf) and Iceman got his power-up on Asgard.

In a past HeroClix (Hammer of Thor) era, I did play a 'Ragnarok' force of nothing but HoT forces (Surtur, Fire Demons, Wolves, Ulik and Rock Trolls) at 1000 points and had fun...but such games can be long.

Edit: I wanted to add something that spins from

4) Asgard as Super-Science

There are occasional references (mostly from the Movies, but also some of the recent cartoons and a few comics) that show villains like Red Skull, Hydra and A.I.M. trying to steal Asgardian magic/technology for their own purposes. I can see them supplementing an 'Attack on Asgard' force, but not necessarily trying to actually take over/destroy Asgard.

We are actually having this game next wednesday, it's a 2000 pt build, and what the judge did is have a sign up sheet with all the major and minor players from Fear Itself, You picked 1 major and 1 minor player from the storyline, and your the only one who gets to use that character in the game. (so there will be only 1 thor in the entire game) The winner takes Asgard, but as we know, Asgard doesn't like strangers, so after you take it, you have to hold the land so you can fill your team out with anyone who wasn't on that list.

I'll try to post how it went next week

This is the game ^ must be from the same venue

Nearly* any combination of four from this list:

Black Panther
Blade
Captain America
Colossus
Daredevil
Deadpool
Doctor Strange
Elektra
Ghost Rider
Human Torch
Iceman
Invisible Woman
Iron Man
Luke Cage
Moon Knight
Mister Fantastic
Ms. Marvel
Nick Fury
Silver Surfer
Spider-Man
Spider-Woman
Storm
Thing
Thor
Wolverine

From Marvel: Ultimate Alliance

* - some combos are not possible due to system exclusives.

Lol lol lol

Okay... That was funny

I was going to say pretty much the same thing:
ha021 Ulik or cm075 Ulik or both depending on the point total.
(Ulik has a big brother.)
ha004 Rock Troll- as many as you can cram onto a team.
The deep dials on the Rock Trolls make them really pushable and combined with their minion power, makes for an annoying and effective swarm team.
This is an awesome idea! I like that theme idea, and now I have to play it.