In reply to Flicka@work:
Linden Avery in the second (and third) series of The Chronicles of Thomas Covenant by Stephen Donaldson...
Plus, of course, The First of the Search, although she has got a fairly flowery name - Gossamer Glowlimn... (from the 2nd series)
You won't have heard of this one, but Rae from Robin McKinley's "Sunshine", a rather good vampire book.
Hermione Granger gets Harry Potter out of no end of trouble in the Harry Potter series
Morgaine in CJ Cherryyh's The Chronicles of Morgaine, and Exiles Gate
(two of the best fantasy fiction books you'll ever read - the first is a collection of three books, so four books, really)
Cayce Pollard in William Gibson's Pattern Recognition
Another Morgaine in The Mists of Avalon by Marion Zimmer Bradley - as in Arthurian legend.
Andromache in David Gemmel's Troy series