Don't forget the
Maxim Gorki (Tupolev ANT-20)
And whilst we're at it no one (certainly not sober, I hope) ever accused the
Douglas C-124 Globemaster II of being a beauty. And let's not forget the
Blackburn Beverley.
The much maligned
Deux Ponts had a certain "je ne sais quoi" in comparison.
We may have a winner with the
Lysander P.12 . It was apparently designed to repel any German invaders in WW2 - I am sure it would have done!
The last one comes from a site I just found which is full of inspiration -
Paul's Ugly Aircraft Shrine.