Hmm... tricky.
A creature of old,
dressed in gold.
Sounds like Glaurung the Golden, Father of Dragons.
Trapped on land,
a nose can’t stand.
??
?? A
nose?
Its fire extinguished,
when against a flaming star it skirmished.
The only one who skirmished a star was Ancalagon
the Black, who fought - and was slain by - Eärendil.
Now, the first five lines all apply to Smaug, I think. He was also called the Gold, I remember a line about "the stench of Smaug" in the Mountain (don't have my books with me), and his fire was extinguished when Bard's arrow knocked him out of the sky into the lake. But neither Bard nor his arrow can be called a star, much less a flaming one, can they?
Still, on the whole, I plump for Smaug. (Fun riddle, and good to see you on the board,
skorp!)