Now these are some ugly birds.

There is something to be said for anything that flies.  That being said, some are more graceful (or, in a few cases, graceless) than others.  Here is one author's list, from historynet.com.

I've got a couple that I'd like to add, however.

The Short Seamew:

Let me just say here that the Short company seems to have had a love affair with ugly airplanes--their boxcar-like cargo birds, for example--but the Seamew has to take the cake. And this was from 1951, when folks should've known better. I don't know if it really flew, or if the ground just rejected it.

Another candidate: The Blom und Voss 141 recon bird. I've always been convinced that this one was designed and built on a dare.

And who can forget the Super Guppy?

Poetry in motion.  Poetry, as in: "I once knew a man from Nantucket..."