This may just be the obvious one - But the least favorite has to be the Battlestar Galactica ending, I had never been so upset by an ending, if this isn't the first thing that comes to peoples minds then I just don't know

Lost.

Sorry. But I liked it

Farscape

Alphas and Reaper. Just when the story was starting to pick up.

Hands down. There were other great shows to get cancelled, but this is the one that hurt the most.

Middleman!

Can Shyamalan get his act together? The trend is not his friend.

I think this worked pretty well as a good mix of the Western with the fantastic.