is there a very large dragon figure out there?

Depending how much you want to put into making your dragon figure. The two figures that come to mine (articulation) would use ML Lizard or Black Heart figures.
McFarland toys has this figure: JYAAKU THE NIGHTMARE
http://www.ebay.com/itm/SPAWN-Dark-Ages ... 589804d30f
This figure is very oriental looking, so it all depends what you are looking for.

OR you can do something like this?


Although, Copperhead figure has scales( http://www.bing.com/images/search?q=DC+ ... A6AA3D6EF1 )and I've planed to change to use that or Black Heart figure to finish off mine. Just gave you some other options for you to think about.

Add the tail and wings from Annihilus and there you have a dragon!

I agree, very cool figure though.

Hydra is cool, but need some articulation. I might go with the foom BAF. Just majorly alter it.

that hydra dragon is cool looking but he is only ten inches tall, probably be a better fit for MU scale.

Biggest on I know of, without getting into lines that are very "kiddy" is Mcfarlane Dragons Hydra.
http://www.spawn.com/features/dragons7/hydra.html
Or Foom BAF.