White Lady was a name used for both Aredhel and Éowyn, but at one point it is also used to refer to Galadriel.

In the chapter "The Window on the West", Book V, The Two Towers, Faramir says to Frodo:

""Yet I envy you that have spoken with the White Lady."

It is only in this one instance that Galadriel is referred to by this name, and whether anyone else ever called her thusly, is not known.
Encyclopedia entry originally written by NellasTaralom