The last post being on the subject of heroic self-sacrifice, I think the transition into talking about Optimus Prime is seamless, here.
I realized the other day while watching Transformers 3 two things: One, the Transformers movies are kind of a lot sexist. As in, kind of a lot actually - particularly the third movie, whose two only female characters delivered an incredibly blunt message: Eye candy girlfriend is useless except as eye candy, also women in charge are terrible and need to get sexed up - preferably by the worthless comedy relief character, because, y'know. Women.
The other thing I realized, however, was a more profound insight. There's something I've always found kinda cool about the Transformers: They're a sexless species. They don't have genders. In fact, their reproduction works in an entirely different way from most species on Earth. We refer to most of the Transformers as male, because... well to be honest, kinda just because men are the default sex in our culture. I thought that perhaps it's because most of the Transformers look male, but actually... not really. They look so different from humans that there's no real way of telling what sex they would be if they had them. Yes, the voice actors in the cartoon are men, but I read the comics so the cartoon voices aren't really "canon" to me - and besides, female bears don't exactly sound anything like female humans, but they're still she-bears.
And then it struck me: Not that human terms really apply to the Transformers, but if we desperately wanted to assign them sexes... wouldn't it make the most sense to refer to Optimus as a woman? After all, Optimus Prime has the Creation Matrix - Optimus is the one who creates new life. The creation of life has, on Earth, in most cultures, been viewed as pretty much the definition of being female.
Optimus Prime is really only set apart from the other Transformers because she can give birth. She is also the one who nurtures, teaches and heals the other Transformers using the Matrix. It marks whoever bears it as a leader, but are we going to call Optimus Prime a man simply because she's in charge?
Optimus Prime is, of course, neither man nor woman because the terms don't apply to Transformers. But if we're going to go with one of them... wouldn't woman be the most logical choice, given the biological functions of Earth females?