Why are most aliens humanoid?

This week will see a series of short posts that ask a question and give a short, simplified answer. Like the blog series baseball joe at fox sports, too short for a full post yet too long for the twitter…

In a lot of mediums, aliens are mostly humanoid. (see: Star Trek, Star Wars, Alien, Predator, The Marvel Universe, etc. etc.)

Why is this?

I simply think it’s because we can’t imagine anything else. And don’t get me wrong, there are plenty of stories with wildly different aliens, including some of the ones I mentioned above.

But it’s also this:

It’s hard to imagine anything else and make it work in a story. Even the some of the weirdest aliens are still more or less humanoid.

So what can we do to fix it?