And another SF thing: Galactic Empires and Gender

So, I've always been a bit bemused by the fascination that SF writers have with Galactic Empires. But just now, something new grabbed my attention. We all know that in history, there's been a number of empires -- some of the more famous and powerful ones in fact -- have been headed by women: Elizabeth, Victoria, Catherine the Great, and so on. But here's the question: in SF literature, story, can one name an interstellar empire run by an Empress?

(note: planetary empires, of the sort headed by the beautiful queen just waiting to be impressed by a strapping Earthman don't count)

Hmm...I honestly can't think of any. And what does this say about Science Fiction and gender?

edit: My beautiful wife did point out a female GE empress: the Ahb empire in the anime/novels Banner of the Stars.