Ungoliant

[Raynor]

We are told in the Silmarillion that she was stayed by the might of Melian, but then this was AFTER she got her eight-legged, gluttonous a$$ beaten by the Balrogs. If She was able to subdue Melkor (thanks to the powerful Trees' sap she drunk dry), I don't see why she couldn't single-handedly destroy Doriath, which was guarded by one Maia. Remember Tulkas and the rest of the Valar were entagled in her darkness during their pursuit, and the horn of Orome faltered. Great is her might, this Ungoliant.

Well, we are only told that the balrogs pursued her, not that they actually fought her. Since she approached Doriath quite soon after that, her power was pretty much intact, yet still no match for Melian.